Bluebird and Small Cavity Nester Conservation
Sialis - Bluebirds and other small cavity nesters
 
bluebirds

eggs
Glossary: What is a ....

Some terminology and ornithological definitions
associated with bluebirds, other cavity-nesting birds and ornithology.

If you see a term I should add, please let me know. Acknowledgements to sources. Also see Acronyms list.

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  • ABA: American Birding Association, publishers of Birding journal.
  • Abdomen: belly.
  • Aberrant: atypical plumage, structural characteristic, or behavior.
  • Abundism: an increase in dark pigmentation in patterned coats or skins which causes an increase in the number or size of pigmented spots, stripes or other patch types.
  • Accidental: a bird or bird species when it shows up outside of its normal range.
  • Accipiter: A genus of hawks characterized by having short, rounded wings, long tails, and long legs. In North America, there are three species - the Northern Goshawk, the Cooper's Hawk, and the Sharp-shinned Hawk.
  • Active Control: With regard to House Sparrows or starlings, refers to aggressive management methods where eggs, nestlings or adults are destroyed - e.g., puncturing eggs so they will not hatch, or capturing and euthanizing adults.
  • Adaptation: In evolutionary biology, any physical structure, physiological process, or behavioral pattern that makes an organism more fit to survive and reproduce in its environment.
  • Adaptive radiation: the evolution of of species adapted to different ecologies and behaviors. For example, aerial specialists like Tree Swallows have evolved tiny feet and short legs, while ducks have webbed feet to enable swimming.
  • Addle: render an egg infertile, e.g., by vigorous shaking. Also used by Purple Martin landlords to describe any rotten, dead or destroyed egg, which they often roll out of the nest cup.
  • Adoption: When a parent, other than the genetic parent, raises or cares for the young of another bird. More info.
  • Adult: in birds, a mature bird that has acquired full characteristic plumage of the species; a Bald Eagle needs 5 years to reach this stage, many swallows take two years, while many songbirds (like bluebirds) are "adult" in one year. Older than a "subadult." Also see SY and ASY. For bird banding, a bird known to have hatched at least 2 years before the calendar year of banding. For some species, sub-adults cannot be distinguished from adults, so birds of both of these age groups become "adults" on their first January 1.
  • Aerial Insectivore: Feeds on insects caught while the bird and insect are flying, like a Tree Swallow. During cold rainy periods, these birds or their young might starve.
  • Agonistic behavior: combative, as in fighting over nest sites.
  • AHY: After Hatch Year (bird age)
  • Airfoil: A structure that creates lift when air flows around it (like a bird's wing.)
  • Air Sacs: Thin-walled sacs extending from the lung bronchi of birds, which fill much of their body cavities. Their function is to increase respiratory volume and efficiency, and also to decrease body weight, adaptations that help make flight possible.
  • Air vent: see ventilation.
  • Alar tract (feathers): includes primary and secondary flight feathers and coverts
  • Albinistic eggs: Eggs that lack normal pigmentation (e.g., white eggs laid by a bluebird).
  • Albino (Albinism): an inherited condition resulting in a lack of melanin pigmentation in the eyes, skin and hair (albinism). Both parents must have the recessive albino gene. Full or partial albino bluebirds have been seen. An albino may be a true albino or a partial albino. Also see leucism. More.
  • Albumen: The egg white (clear part), which provides protection (cushioning), water and protein for the developing embryo. It has multiple layers: outer liquid, dense albuminous sac, inner liquid, and chalaziferous. The firm albumen holds the inner thin white and the yolk, and adheres to the shell membrane on each end of the egg.
  • Allofeeding: When one bird passes food to another bird (typically an adult), with or without solicitation. More.
  • Alloparenting: When an individual, other than the genetic parent, provides care for young of the same species. More info.
  • Allopatric: Occuring in differetn geographic areas. Also see Sympatric.
  • Allopreening: When one bird preens another. May solidify a relationship between individuals.
  • Alpha codes: four letter shorthand used to indicate a bird species. E.g., the alpha code for Eastern Bluebird is EABL. There are also six letter codes for scientific names.
  • Alternate plumage: Temporary additions/colors during breeding season in birds that have two molts per year. Sibley says that unless the prealternate molt is complete, breeding season plumage is a combination of alternate plumage and unmolted (retained) basic plumage.
  • Altricial: as in Nestlings. Altricial birds are either naked or have very sparse down at hatching. They usually have their eyes closed at hatching, are fed by their parents for some period of time, and may stay in the nest for an extended period after hatching. Opposite of precocial.
  • Altruistic behavior : When one bird apparently puts itself at risk or makes a sacrifice to help another without any direct benefit to itself. An example is when fledglings from a previous brood help feed siblings from a subsequent brood. (There may be a selfish aspect to this in that they learn how to rear nestlings.)
  • Alula: A small group of feathers attached to the first "finger" (at the bend) of the wing. Their function is to reduce turbulence and drag, and also assist with braking and steering.
  • AMKE: American Kestrel.
  • Anisodactyl feet: three forward toes and one rear toe - found on most perching birds. See Zygodactyl feet.
  • Anting: When a bird picks up ants and rubs them vigorously on its plumage (active) or lays on top of an anthill and lets ants crawl on its body (passive). More.
  • Anthropomorphize: To ascribe human characteristics to something nonhuman like a bird.
  • AOU: American Ornithologist's Union, publishers of The Auk and The Check-list of North American Birds. Considered the standard authority for bird naming and systematics.
  • AOU Number: Used in bird banding, numbers assigned to birds by the American Ornithologists' Union and published in the Check-List of North American Birds, 1983 Edition
  • Apartment tree: Tree with multiple cavities, where each cavity is sometimes used simultaneously by different species as in Violet-green Swallows.
  • Appeasement display: signaling submission to a dominant bird, as when starlings crouch, lower their head and turn away from an opponent.
  • Apteria: Areas of a bird's skin from which no contour feathers grow. Apteria are sometimes covered by down feathers, but may not be visible because the feathers cover the naked areas.
  • Arachnid: a class of invertebrates that have eight legs, instead of six. E.g., spiders, mites.
  • Arboreal: living in trees
  • Arthropod: Insects, crustaceans, spiders and other members of the phlym Arthropoda.
  • Aspect ratio: the wing's length divided by its width - used to measure wing shape.
  • ASY: after second year - a bird two or more years old. For Purple Martins, considered an adult.
  • Asynchronous hatching: hatching that does not occur at the same time, but that may take place over a two to three day period. Usually the younger chicks only survive if food is abundant. Common in Red-cockaded Woodpeckers. Also in Tree Swallows where incubation begins on the penultimate egg.
  • ATFL: Ash-throated flycatcher.
  • Attendant Species: Birds that tend to accompany bluebirds, such as house finches, goldfinches, and yellow rumped/pine warblers. (Wannabes)
  • Attraction Spot: a black spot, 1.5"-2" in diameter, painted or made with electrical tape/felt attached to the roof (and sometimes sides) of a nestbox. Some believe it helps birds recognize the nestbox as a cavity from a distance.
  • Auriculars: feathers covering the side of the head including the ear openings. Also called Cheeks or Ear Coverts. This set of feathers conveys sound into the ear.
  • Auxiliary Marker (or color marker): In bird banding, a marking device other than the standard metal leg band. Includes colored neck and leg bands, paints, dyes, leg or wing flags or streamers, tags, nasal discs, and radio transmitters.
  • Avian: referring to the class of animals named birds.
  • Avian flu: (influenza), also called Bird Flu or H5NI virus.
  • Aviary: Typically a large, enclosed facility where birds are kept in captivity, but can fly about. Sometimes wildlife rehabbers will keep birds that can not be released in an aviary.
  • Aves: The Latin word for "bird" and also the name of the class of animals that consists exclusively of birds. Bluebirds are in the class Aves, the order Passeriformes (perching birds), the family Turdidae (Thrushes and Allies), genus: Sialia (a kind of bird), species (3), subspecies (14 or 15 depending on whose list you use) - see more info.
  • Avifaunas: large groups of birds in regions of the world - see Faunal Regions.

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  • Babesiosis: a still uncommon disease transmitted by deer ticks.
  • Bachelor Male: A male that has not yet found a mate and thus is not breeding. Bachelor Male bluebirds may sing plaintively for days on end trying to attract a female.
  • Backcross: When a hybrid mates with one of their parent species.
  • Baffle: A device placed below a nestbox or a feeder to deter predators such as snakes, raccoons, mice and squirrels.
  • Banding: An aid to studying wild birds, where a small individually numbered metal or plastic ring (band) is attached to an individual's leg or wing, to find the same individual later and study migration, longevity, mortality, population studies, feeding behavior, etc. Sometimes called "ringing." A permit is required to band native birds. More info.
  • Barbicels: Little hooks on barbules that interlock wtih adjoining barbules to form the feather vane.
  • Barbs: The part of the feather that branches sideways off of the rachis.
  • Basic plumage: plumage renewed after breeding. Temporary additions (for breeding season) are called Alternate plumage. (Note: some species have one molt per year, called the prebasic molt, some have two.)
  • Bathing: Getting wet via splashing or light rain (e.g., deliberately sitting on a wire exposed to precipitation)
  • BBL: Bird Banding Laboratory.
  • BBS: See Breeding Bird Survey.
  • BCCH: Black-capped Chickadee.
  • Beak: see Bill.
  • Begging: Nestlings, and young that have fledged from a nest may beg for food, by stretching out their neck and opening their beak. Fledglings may utter a special call and flutter their wings. Females may also beg from males as part of courtship or pair bonding.
  • Bergmann's Rule: a principle that asserts that body mass in warm-blooded animals increases with higher latitudes and colder temperatures. More info.
  • Best of Bluebird_L Classifieds: Email posts, archived by topic, from the Bluebird_Listserv.
  • BHCO: Brown-headed Cowbird.
  • BHNU: Brown-headed Nuthatch.
  • Biconical: an egg shape where both ends are tapered (pointy) like a grebe egg.
  • Bigamy: One male mates is mated with two or more females.
  • Biliverdin: and the zinc chelate of biliverdin are two of three pigments responsible for egg coloration. These pigments produce blue-green colors.
  • Bill: Beak or mandible (upper and lower). The bony modification of the bird's skull used for picking up food and nesting material, and for preening feathers. The bill acts as both lips and teeth, neither of which are found in birds. It also acts as a "hand," as many objects are picked up with the bill. Covered with a horny sheath.
  • Bill fencing: stabbing at another bird with its bill, or running towards it with bill outstretched (starlings may do this.)
  • Bill snapping or Beak clicking: A sound or call made by adult bluebirds that may indicate distress or alarm or warning. Bluebirds and Tree Swallows may do it when flying by, usually during monitoring, probably either as an alarm sound or an attempt to frighten intruders. It tends to increase just prior to fledging as this is a vulnerable time for young. The female may also use it to call to young to encourage fledging (male may sing.) Starlings often clack or rattle their bills as part of their warbled song. Different from a social chatter noise.
  • Bill-sweeping or sweeping: a display in which a pair of birds sweep their bills back and forth over the bark near their nest hole. Often the birds have crushed insects in their bills. Typical behavior of species such as White-breasted Nuthatch. Bill-waving or head-swinging by Downy Woodpeckers often indicates aggression.
  • Bill tilt: (also called bill point, head-up, flight bill-point) Bird crouches with head back and bill up, legs straight, bill-head-neck-body vertical with feathers sleeked - usually towards subordinate bird of same sex in Cowbirds.
  • Bill wiping: usually occurs at the end of feeding, may also signal appeasement (e.g., in starlings) or a displacement behavior.
  • Bioaccumulate: accumulate in a biological system. Commonly refers to the cumulative uptake of toxic substances such as DDT that can stay in a biological system such as a fish.
  • Biochrome pigments: naturally occurring chemical compounds that absorb light and reflect energy back to produce the colors we see. The three major types are melanin (earth tones like gray, black, brown and buff), carotenoids (which come from a birds diet and produce bright yellows, oranges, reds except in parrots [e.g., on Male House Finch], some blues and greens) and porphyrins (bright brown e.g., in owls, green and magenta).
  • Biodiversity: (1) The variety of life forms, the ecological roles they perform, and the genetic diversity they contain (2) The variety from molecular, population, and interspecific levels up to the heterogeneity of ecosystems and landscapes (synonym: biological diversity). More.
  • Biogeography: the study of geographical distributions of plants and animals. Biogeographers divide the Earth into faunal regions that roughly correspond to the major continents.
  • Bipedal: with two legs
  • Birdality: the equivalent of the "personality" of an individual a bird (I made this word up.) More.
  • Bird Banding Laboratory: The US office that is involved in issuing banding permits, bands, and auxiliary marking authorizations for the USA. A part of the United States Geologic Survey, Biological Resources Division, Patuxent Wildlife Research Center.
  • Bird Brain: Large and well-developed (6-11 times larger than that of a similarly sized reptile), which exhibit functional lateralization.
  • Bird Guardian: A commercially available plastic tube that is inserted into a nestbox hole to prevent raccoons, cats and birds from preying on contents. A newer version screws onto the outside of a nestbox. May deter nesting birds.
  • Birdhouse: another name for a nestbox.
  • Bird Skin: taken from a bird specimen for preservation and scientific study, posed lying on its back with legs crossed. Compare to whole mount.
  • Blood spot: A red spot sometimes found on an egg yolk, also known as the meat spot.
  • Blood feather: an immature feathers that still has a blood supply to the shaft. They have a dark-colored shaft, as opposed to the white or clear shaft of a mature feather.
  • Blowfly: Protocalliphora sp., an insect that parasitizes birds. The larvae suck blood from nestlings.
  • Bluebird trail: a series of nestboxes placed along a prescribed route (often in a line, circle, square, or grid pattern). Usually five or more boxes.
  • Bluebirder: A person interested in raising bluebirds (e.g., by putting up nestboxes), as opposed to birders in general. First used by Dick Tuttle in the 70's?
  • Bluebirding: Usually refers to people who are engaged in trying to increase bluebird populations by putting up nestboxes or a bluebird trail. First used by Dick Tuttle in the 70's?
  • Bluepers: Mistakes made by bluebird host, with good intentions but unexpected and disappointing (and sometimes embarrassing) results. Linda Violett may have used it first. See Downside.
  • Bolt (Mel) trap: An inbox trap cage that attaches to the inside of a nestbox door. The bird is removed through a small door built into the hardware cloth.
  • Bolus: packing insects into a ball or lump to carry back to the nest to feed young (Tree Swallows do this - I wonder if they use their saliva to glue them together?)
  • Boreal: associated with northern coniferous forests of Canada and Alaska.
  • Bottomland: low-lying land along a stream, river, or brook.
  • Bow: (also called topple-over, song spread) feathers ruffled, chest raised, wings lifted and spread, tail spread and bows forward (sometimes followed by bill wipe and song in Cowbirds). When agonistic (e.g., with other males) may be associated with bill-tilts and supplanting.
  • Box depth: The interior distance from the roof to the floor of the nestbox.
  • Breast: The feathers along the front of the body, from the neck down.
  • Breast Band: stripe across the breast.
  • Breast Spot: small, differently colored area on breast
  • Breeding Bird Survey (BBS): began in 1966 to systematically monitor bird populations in North America on an annual basis. It is conducted in June. Data is used to make maps. Coordinated by the U.S. Geological Survey adn the Canadian Wildlife SErvice.
  • Breeding cycle: the time period beginning at nest building, through egg laying and raising young, to the point of independence
  • Breeding dispersal: the year-to-year movement of an adult bird from one nest site to another.
  • Bristles: Long, stiff, specialized feathers that have sensory and protective functions. They have a stiff, tapered rachis with a few basal barbs. Semibristles have more side branches. Usually found on the head (near mouth and eyes), also on toes of some owls. Most aerial insect eating birds have bristles and semi-bristles around their mouths, on woodpeckers they cover the nostrils.
  • Broken Wing Display: Adult (usually female) protecting young walks along ground with wing drooped down, while quivering and vocalizing to distract predators (e.g., Prothonotary Warbler.)
  • Brood (n): the young of a bird that are hatched or cared for at one time. (v): to sit on and keep warm (nestlings or chicks).
  • Brood parasitism: An interaction between two species in which one species gains at the expense of the other. Example: when a bird lays an egg in another bird's nest. Can be intraspecific (same species) or interspecific (other species.) See obligate brood parasitism and egg dumping.
  • Brood patch: A bare, flaccid patch of skin on the bird's belly region (and sometimes part of the breast), where downy feathers either fall out, or are plucked out by the female just before she begins incubating. It becomes engorged with blood vessels during breeding season, and works like a hot water bottle to transfer heat from the parent's body to the eggs. See photo.
  • Brood Reduction: An adaptive strategy which maximizes the number of healthy fledglings. When more eggs are produced than can be raised, and there is not enough food for all, later hatching young or runts, which are weaker and smaller than nestmates, starve or are neglected or are attacked by siblings (siblicide.)
  • Broody: a female bird wishing or inclined to incubate eggs.
  • Buccal Cavity: the space inside the mouth.

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  • CACH: Carolina Chickadee.
  • Caching: hiding and storing food - e.g., in the crevices of bark and under leaves. Retrieval of cached food items is not accidental, as in scatterhoarding. For example, Black-capped Chickadees can remember the location of the stored food for up to a month after hiding it.
  • Call: A vocalization used for alarms and contact. Generally shorter and simpler than songs. Especially important in birds that feed or migrate in flocks. Pitch (high or low, rising or falling); quality (harsh, clear, liquid, buzzy, etc.); and rhythm (fast, slow, choppy, etc.) are used to characterize calls.
  • Calamus: the quill of a feather that anchors it in the skin.
  • Call-matching: The male and female duplicate each other's flight call (in finches.)
  • Candidate: Before being added to the official list of threatened or endangered species, there is a category of 'candidate.' A species can remain a 'candidate' for years while the experts try to come to agreement.
  • Candling: Shining a light through an egg to see whether it is developing or not.
  • Cap: Top of the crown.
  • Capital tract (feathers): feathers on the head
  • Carnivore: An organism that eats meat/living animals.
  • Carnivorous: subsisting or feeding on animal tissues. Carnivorous birds have strong, hooked beaks for tearing flesh and muscle.
  • Carrying Capacity: The ability of an ecosystem to support or sustain a certain population size (before it becomes overpopulated.) It can be altered (e.g., by loss of habitat, introduction of more food sources.)
  • Carotenism: ? abnormalities involving the carotenoid pigments, including distribution or amount as well as the shift from red to yellow (e.g., in House Finches.) Extreme cases of all yellow birds, probably due to melano-carotenoid schizochroism (e.g., in caged birds bred for color) are referred to as 'leutinos' or 'lutinos?' by aviculturists.
  • Casual: Seen occasionally, but not regularly occurring in a region. Not likely to be seen each year.
  • Caudal tract (feathers): includes the retrices and coverts - i.e., tail feathers
  • Cavity: a hole or opening in a tree trunk or limb, or fence post etc. Either excavated (e.g., by woodpecker) or a natural cavity found in a snag or dead/dying tree limb.
  • Cavity adopter: Birds that use cavities already created, like Purple Martins and Tree Swallows.
  • Cavity-nester: A bird that nests in holes in trees or other structures, or in nestboxes. Also see primary and secondary cavity-nester.
  • CARW: Carolina Wren.
  • CBC: Christmas Bird Count, conducted by citizen scientists and reported to the Audubon Society. Data is used to generate maps.
  • CBP: see Conspecific Brood Parasitism
  • CBCH: Chestnut chickadee.
  • Ceca: See singular Cecum
  • Cecum: Small side sacs near the end of the digestive tract in some birds that help with digestion, especially of fibrus plant foods. Bacteria in the ceca further digest and ferment partially digsted foods into useable compounds absorbed through the cecal walls. This organ also produces antibiodies, aids water absorption and metabolism of uric acid into amino acids.
  • Centrifugal tail molt: Replacing tail feathes, starting from innermost to outermost feathers (as in most passerines.)
  • Cere: Fleshy area between the beak and face.
  • Chalaza (egg): The layer of the egg "white" that immediately surround the yolk. It is a firm but very thin layer of albumen.
  • Chaparral: Dense brushy habitat of woody shrubs wtih small, thick evergreen leaves.
  • Characters: traits shared as result of common ancestry, e.g., the arrangement of toes. Unique characters define closely related groups of species. Conservative characters don't change easily in the course of adaptation. Ancestral (primitive) vs. changed (derived) characters are also used to figure out taxonomic relationships.
  • Chasing: When a bird actively follows another bird with other aggressive behaviors before and during.
  • Check (egg): An egg that has a broken shell or crack but the shell membranes are still intact and the contents are not leaking.
  • Cheek: See Auricular.
  • Chest: the front part of the body.
  • Chick: the young of any bird,used especially for a young chicken.
  • Chin: part of the face under the bill.
  • Chitin: Horny material that farms part of the hard outer integument of insects, arachnids and crustaceans.
  • Christmas Bird Count (CBC): Annual bird monitoring program done in late December and early January. Done by volunteers, coordinated by the National Audubon Society.
  • Citizen Scientist: A volunteer (regardless of age, location, or experience) involved in gathering data about our environment. The source of much CBC data.
  • Cladistics: the study of evolutionary branching sequences. It enables ornithologists to sort across taxa, and looks at primitive and derived characters.
  • Claim straw: a piece of grass placed in a nestbox, perhaps to signal intent to "claim" the box.
  • Claw: the horny structure on the end of a bird's toe (like a toenail.) Used to grasp food and cling.
  • Cloaca: The common cavity into which the intestinal, genital, and urinary tracts open in birds. Sperm are transferred when the male briefly touches his swollen, sperm-containing cloaca to the cloaca of a receptive female.
  • Cloacal kiss: during copulation, when the male brings his cloacal opening in contact with the female's, and ejaculates sperm to fertilize eggs.
  • Clutch: total number of eggs laid by a female bird in one nest attempt. Also called a set.
  • Clutch-initiation date: date on which the first egg in a clutch is laid.
  • Cock: Male bird. Usually refers to gallinaceous birds like domestic chickens. Opposite of hen.
  • Collar: Rear portion of the crown. Nape/hindneck.
  • Collecting: Gathering nests, eggs or killing birds for science. Controlled by the Migratory Bird Treaty Act. Federal and state permits, plus a project proposal, are now required before a scientist can collect birds.
  • Colony: a group of birds nesting together in close association, such as a Purple Martin colony.
  • Colonial nester: A species that nests in colonies.
  • Color Morph or Phase : See Polymorphism. Certain species may have two or more variations in their plumage, presumably under genetic control. For example, Snow Geese may exist in either the white or blue color phases. Color morphs are usually found mainly or exclusively in certain populations.
  • Common name: An unofficial name that is not the scientific name. For example, the common name of Sialia mexicana is the Western Bluebird.
  • Communal nesting: Several females place eggs in one nest, and all adults care for the young. See Cooperative Breeding.
  • Complete molt: All tracts of feathers are rplaced in a short time. See partial molt.
  • Complete paternity: when all offspring as genetically related to one male. Compare to partial and zero paternity.
  • Conduit (EMT): hollow metal pole used for electrical wires. Some people use it to mount a nestbox.
  • Conical Baffle or Coolie Hat baffle - a cone shaped baffle placed on a mounting pole to deter climbing predators and snakes. More info and instructions.
  • Coniferous: evergreen trees that bear cones, such as pines, firs, spruces, etc.
  • Conservation: Managing natural resource use, allocation, exploitation, and protection to maintain the health of the natural world or ecosystem.
  • Conspecific: of the same species. See conspecific or intraspecific brood parasitism (egg dumping)
  • Conspecific Brood Parasitism: egg dumping - when a female bird lays her egg(s) in the nest of another bird of the same species. More.
  • Contour feather: predominant feather type found on the body, wings, and tail of the bird (as opposed to other feather types: down, bristles, semiplumes, etc.) Usually have a long central shaft with a broad, flat vane on either side.
  • Convergence: the independent evolution of similar adaptations in unrelated organisms, so that they are superficially similar (e.g., in appearance or behavior.)
  • Cosmopolitan: found widely throughout a region; a species with worldwide distribution.
  • Countershading: Light underparts and dark upperparts of plumage disguise the outline of a bird, aiding in concealment.
  • Counter-singing: The territory holder matches a neighbor or stranger's song phrase by phrase to establish territory boundaries.
  • Coverts: rows of smaller feathers that overlap flight feathers and cover the gaps between them.
  • Cooperative breeding: where individuals other than the male–female pair (i.e., parents) help to raise a single brood (Brown 1987). May consist of two females rearing broods in the same nest simultaneously, and/or non-breeding birds serve as helpers at the nest of one or more breeding pairs. Non-parental adults, called extra-pair helpers, auxiliaries or supernumeraries, usually do not breed themselves. More.
  • Copulation: The physical act of mating. In most birds, the male lands on or climbs onto the back of the female, and then both birds touch their exposed cloacas together (called the cloacal kiss.) The sperm from a Purple Martin is stored in the oviduct and can continue to fertilize ova for up to a month.
  • Copulatory Display: When the female invites sex, e.g., in Downy Woodpeckers when the female flies towards a male and perches on a brach, holding head and tail up (exposing cloaca) and dropping wings slightly.
  • Courtship: Early in the breeding cycle, when male and female birds are choosing or bonding with their prospective mates. Allofeeding may occur in some species like bluebirds.
  • Covert: body feathers which overlie the bases of the flight feathers on the wings and tail. Also applies to the feathers covering the bird's ear region.
  • Cranial kinesis: The ability to flex or bend the upper half of the bill (Zusi 1984).
  • Crepuscular: active at twilight, dawn, and dusk.
  • Crest-raising: A display (e.g., by Downy Woodpeckers) where feathers on the top and back of the head are displayed - sometimes during aggressive interactions. May be done by both males and females, may occur in association with other displays.
  • Crissum: triangular area of feathers on the undersurface of a bird between its vent (anal opening) and the base of its tail feathers.
  • Crop: A specialized organ that is an enlarged part of the oesophagus, where food is stored until it can be digested later. Highly developed in seed-eating birds. See gizzard.
  • Crowded Single Boxes: BRAW term for boxes from 100 feet to 100 yards apart.
  • Crown: covers the top of the bird's head.
  • Crural tract (feathers) on the lower leg
  • Culmen: central ridge of the maxilla, extending from the forehead to the tip of the bill.
  • Cup: With regard to nest shape, a deep depression, with a rim height several times the diameter of the eggs. See nest cup.
  • Cupping or Cup Molding : Female uses her chest and wings to form the cup in a nest. (I made this term up.)

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  • Data Logger: a field device that records weather data from one or more external sensors. E.g., used to monitor temperatures inside a nestbox.
  • Dawn Serenade or Dawnsong, Dawn Chorus: a bout of singing by the male in the pre-dawn (full darkness)/early morning to signal the mate or announce territory (e.g., in Mountain Chickadees)
  • DDT: Dichlorodiphenyltrichloroethane. Organic pesticide, banned in the U.S., but still used in some other countries.
  • Deciduous: a plant with broad leaves that fall off or shed either seasonally or at a certain stage of development in the life cycle, e.g., oaks, maples, poplars, hickories, magnolias, etc.
  • Decorative nestbox: A nestbox primarily designed for looks (e.g. think Birds & Blooms magazine), and not necessarily suitable for use for cavity-nesters. May actually result in death (e.g., if it is too deep, not properly ventilated, etc.)
  • Decoy: A live House Sparrow used inside a ground trap to attract other House Sparrows.
  • Deer tick: A tiny tick (Ixodes sp.) that can transmit Lyme disease.
  • Definitive plumage: mature plumage.
  • Delayed dispersal: tendency for offspring to stay at or near home rather than look for a new place to live and breed. Same as natal philopatry.
  • Desert: region getting less than 10 inches of rain per year.
  • Determinate (egg laying): the number of eggs produced by a species is determined at the onsite of laying and is not changed by removal or addition of eggs. Also see indeterminate. More.
  • Detritus: in a nest, organic waste material from decomposing nesting material, feathers, etc. May attract fire ants.
  • Decurved: Curved downward (as in a bill.)
  • Dichromatism: individuals have one of two distinct plumage color types. See dimorphism.
  • Digiscope: A digital camera with significant magnification capabilities, kind of like a binocular combined with a camera lens.
  • Dimorphism: existing in two forms (size, shape, color, or other characteristics.) Also see sexual dimorphism.
  • Diurnal: of, relating to, occurring, or active in the day. Diurnal birds may still migrate at night.
  • Dispersal: movement away from a site where it hatched (natal dispersal and juvenile dispersal), and adults moving from one breeding location to another (breeding dispersal.)
  • Displacement behavior: self-directed self-grooming, touching, scratching or vocalization when an animal has a conflict between two drives, like a desire to attack while being fearful (e.g., of a dominant human) at the same time. A measure of anxiety. For example, when a human checks a WEBL nest, the parent may go off on a perch and engage in bill-wiping.
  • Display: Ritualized signal intended to convey a specific message.
  • Distal: Farther away from the center part of the body.
  • Distribution: Are or range where a species is found.
  • Divorce: when at least one partner repairs with another individual while both partners are still alive (e.g., because they found a better quality mate.)
  • DNA-DNA Hybridization: compares genetic change that has taken place between two groups that came from a common ancestor.
  • DNA fingerprinting: using genetic markers to determine identify and study parentage, etc.
  • Dorsal: the back or upperparts.
  • Down: soft fluffy feathers (plumulaceous) that provide thermal insulation.
  • Dummy nest: A nest not used for breeding, generally constructed by a male (as in House Wrens). May or may not be used by the female who reconstructs it. When constructed by House Wrens they lack a lined nest cup. May be used to attract females to territory, distract predators or nest-parasitizing birds like cowbirds. More.
  • Dumping: see Egg dumping.
  • Dustbathing: Taking a "dry bath" in a little dustbowl. E.g. a House Sparrow bends its legs, leans forward on the chest, and throws up soil or water with the bill or wings. Sometimes wings are extended, shuffled in the soft soil and brought upward full of dust, which lands on the fluffed-up body feathers.
  • Drain(age) hole: A hole in the bottom of a nestbox that allows water to leave the interior.
  • Drip edge or Rain groove: a saw kerf on the underside of a the nestbox roof that directs water away from the entrance hole. tapping
  • Driver hypothesis: suggests that exotic species can displace native species, steering the competition of species to a less diverse endpoint. Contract to "passenger hypothesis." (from Birdscope Spring 2007)
  • Drumming: also called tattooing, and rapping. Used to communicate with members of the same species (e.g., Downy Woodpeckers.) More.
  • Dwarf Egg: An egg that is smaller than usual (not common). They often lack a yolk, and thus will not hatch. They may be more spherical than a normal egg, and have a thick, rough shell.

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  • EABL: Eastern Bluebird.
  • EASO: Eastern screech owl.
  • Ecosystem: naturally occurring group of organisms (plant, animal and other living organisms—also referred to as a biotic community or biocoenosis) living together with their environment, functioning as a unit of sorts.
  • Ecotone: Habitat created by juxtaposition of different habitats that merge together (may be used by "edge" species like cowbirds.)
  • Ectoparasite: An organism that lives on the surface (outside) of the body of a host organism to the detriment of this host. An example is a blow fly larva.
  • Edge: habitat that occurs at the boundaries between different types of land cover, such as a forest and a meadow.
  • Egg: an egg is the zygote, resulting from fertilization of the ovum. It nourishes and protects the embryo. Oviparous animals are animals that lay eggs, with little or no other development within the mother.
  • Egg bound: the hen is unable to pass an egg that has formed. The egg may be stuck near the cloaca, or further inside. Egg bound is a reasonably common, and potentially serious, condition that can lead to infection or damage to internal tissue. The bound egg may be gently massaged out; failing this it may become necessary to break the egg in situ and remove it in parts. If broken, the oviduct should be cleaned of shell fragments and egg residue to avoid damage or infection.
  • Egg Cry: noise made by some species during egg laying. E.g., a female House Finch issues a loud, continuous egg cry during laying.
  • Egg dumping: when a female deliberately lays her egg(s) in the nest of another bird, sometimes creating very large clutches, e.g., chickadees (also called conspecific brood parasitism). Also see obligate brood parasitism - e.g., cowbirds). More info.
  • Eggnant: A fun term coined on the Bluebird Nut forum for a female bird that is expecting.
  • Eggshell: The hard calcium shell, secreted by the bird's shell gland, that surrounds and protects the ovum. It is porous, allowing oxygen in and carbon dioxide out.
  • Egg tooth: a sharp, hard rasp structure that forms on the bill tip of a hatchling that enables the baby to break through the egg shell. After a few days it is sloughed off/reabsorbed.
  • Egg tampering: rendering eggs infertile, by puncturing, boiling, microwaving, addling, etc. An example of an active House Sparrow control method.
  • Ehrlichiosis: a still uncommon disease transmitted by deer ticks.
  • Elevator Trap: A ground trap where the bird steps into a moving chamber which then drops down. If they want to get out of the chamber, they have to enter the trap.
  • Elliptical (egg shape): elongated with equally rounded ends, broadest in the middle. Long, normal or short (almost round) forms.
  • Encounter: For bird banding, handling a banded bird, alive or dead, or a report of a band subsequent to initial banding.
  • Endangered species: in danger of extinction throughout all or a significant part of its range. (ESA 1973. States may have their own definitions.)
  • Endoparasite: an organism that lives inside the body of a host organism to the detriment of this host. E.g., a tapeworm.
  • Endothermic: Warm-blooded, capable of maintaining high body tempreatures even when the ambient temperature varies.
  • English Names: recommended standardized names in English prepared by the Internatinoal Ornithological Congress. Also see Scientific Names.
  • Erythrism: an unusual pigment condition, where birds appear more reddish or rufous than others of their kind. Some species have a commonly occurring rufous form, e.g., the Eastern Screech-Owl.
  • Ethology: the scientific study of animal behavior considered as a branch of zoology. A scientist practicing ethology is called an ethologist.
  • European paper wasp: Also see native paper wasp. Polistes dominulus. A non-native wasp that builds a paper nest that usually hangs downward and has open cells on the bottom. May build nests inside birdhouses. First found in the U.S. in Massachusetts around 1980. Since then, it has spread in southern New England and south to Maryland, north to Maine, and west to Michigan and Ohio, California and Washington State.
  • EUST: European starling.
  • Euthanasia: A humane death that is quick, effective and minimizes stress and suffering.
  • ETTI: (Eastern) Tufted Titmouse - sometimes referred to as TUTI.
  • Excavators: Birds that make their own cavity for nesting.
  • Exodus: Birds taking off for migration.
  • Exoskeleton: the harder outer body layer of an insect or arthropod. Grit helps birds pulverize this part.
  • Exotic: Non-native (introduced) species.
  • Exploitative Competition: Individuals preferentially use a resource (like a nestbox), thereby depriving others of its benefits. Also see Interference Competition.
  • External pipping: See pipping.
  • Extinction: the complete and total dying out of all members of a species.
  • Extirpated: a species that is locally extinct in an area where it was once found, but still exists in other states.
  • Extra adult: a non-breeding adult that interacts frequently and non in a nonhostile manner with the primary breeding pair at or near the nest, regardless of whether they care for the young or later breed.
  • Extra-pair copulation: For a pair bonded bird (e.g., one that is nesting), mating with a different male or female. Male bluebirds try to prevent this by guarding their mate.
  • Extra-pair fertilization: Fertilized egg resulted from an extra-pair copulation.
  • Eye line: line of feathers in front of or behind eye. Carolina Wrens have a more prominent eye line than House Wrens.
  • Eye ring: pale colored feathers around the eye. In bluebirds, juveniles have a white eye ring.

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  • Facultative: optional - occurs in some members in some years or situations. E.g., birds move different distances in different years depending on food variability.
  • Fallout: Premature fledging. Also when birds are migrating, but due to weather conditions, stop and pile up in a few locations.
  • Fallout shelter: Purple Martin landlords use these to catch young that prematurely fledge. Parents will not feed nestlings unless they are up off the ground.
  • Family (name): A taxonomic grouping. Family names end in "-idae." For example, all woodpeckers are in the family Picidae.
  • Faunal Regions: Australasian (Australia and New Guinea), Ethiopian (Africa south of the Sahara), Nearctic (North America), Neotropical (Central and South America), Oriental (Southeast Asia), and Palearctic (Europe and Asia). Each region has characteristic birds. The U.S. is in the Nearctic Faunal Region. Also referred to as Avifaunas.
  • Feather: One of the epidermal growths that collectively form plumage. See primaries, secondaries and coverts. Filamentous, soft, flexible and lightweight. A fully grown feather is dead, with no nerves, muscles or blood vessels beneath the outer surface. Types of feathers include contour, flight, down, semiplumes, filoplumes, bristles and powderdown.
  • Feather germ: the tubular bump where feather growth begins with a thickening of the skin cells.
  • Feather tracts: dense concentrations of feather attachments (pterylae), separated by areas of skin with no feathers (called apteria).
  • Fecal glue or glop: a mucky buildup of excretions in a nest. May be associated with excessive consumption of earthworms. See photo.
  • Fecal sac: a clean, tough mucous/gelatinous membrane/film containing the excrement of nestling birds. Sort of like a birdie diaper. Early sacs may be eaten by parents for extra nutrition as the very young nestlings can not completely digest their food. Parents can be seen removing them from nestboxes, and usually drop them away from the nest e.g., about 100 feet in Purple Martins. (Tree Swallows may drop them in water.) More info.
  • Femoral tract (feathers): on the dorsal side of the thigh
  • Feral: escaped from domestication and gone wild. Often used to refer to feral cats that live outdoors (free roaming) and are not owned/kept as pets.
  • Fertilization: Merging of sperm and ova. In birds, this takes place after copulation in the upper end of the female's oviduct.
  • Fidelity: staying with the same mate over time (more), or returning to the same area to breed (called nest-site fidelity.)
  • Fighting: When birds fight, they often strike with spread wings, peck, scratch, and sometimes lock feet and hold their opponent's feathers in their bill.
  • Filoplumes: hairlike feathers used to monitor the movement and position of adjacent vaned feathers. Particularly found on the back of the neck.
  • Fire ant: Four species of fire ants are found within the contiguous southeastern United States. The tropical fire ant, Solenopsis geminata Fabricius, and the southern fire ant, S. xyloni McCook, are considered "native." A black fire ant (Solenopsis richteri Forel) and a very aggressive red fire ant (Solenopsis invicta Buren) are introduced.
  • Fledging: The act of leaving the nest. See fledgling.
  • Fledgling: A young altricial bird that has left the nest. Young birds are said to have "fledged" when they have completely acquired their first true feathers and have left the nest. They may be referred to as "fledglings" from the time they leave the nest until they are completely independent of all parental care. They often have short wings and a short tail. They may not be able to fly well.
  • Flight feathers: The long feathers of the wings and tail.
  • Floater: An unattached adult (not paired) that may challenge a breeding bird for a nest site.
  • Flock: a large group of birds. Special terms may be applied to certain species - e.g., a flock of geese is called a gaggle. More.
  • Flutter Display: Aerial version of the wing-spreading or wing-threat display, where a bird (e.g., Downy Woodpecker) flies like a bat or moth over or towards another of its species, usually during breeding season. Primarily by male during pair formation, or in aggressive context.
  • Flyway: the aerial flight path of migrating birds.
  • Follicles: new feathers grow from these specialized pockets of skin cells.
  • Foraging: looking for food.
  • Foraging style: The way birds hunt or scout for food. E.g., Eastern Bluebirds perch and drop to the ground for food, Western Bluebirds hover, Tree Swallows capture bugs on the wing.
  • Forbs: Nonwoody, nongrassy plant species found in teh understory and ground layer - e.g., wildflowers.
  • Forehead: Part of the face above the eyes.
  • Forest: Habitat dominated by trees. Maybe deciduous, conferous, mixed, open or true (with a closed canopy at least 30 feet high)
  • Forest fragmentation: occurs when large, contiguous blocks of forest are broken up into isolated islands by development, roads, or clearing for agriculture.
  • Form: A morphologically distinct group of organisms (taxon or unit of classification)
  • FoNS: Formula for nestling songbirds, used by licensed wildllife rehabbers.
  • Forstner bit: A specialty wood cutting bit often used to make entrance holes in nestboxes. It rides on semi-circular spurs and produces a clean, flat bottom hole. Can be used with a drill press. Better than a paddle bit or hole saw for a clean hole.
  • Fostering: Placing an egg or a baby bird in the nest of another bird of the same species in order to enable it to survive (e.g. when the parents are killed). Nesting must be at the same stage of development.
  • Foster parent: When an individual, other than the genetic parent, provides care for the offspring of another parent (of its own species or another species.) More info.
  • Fright molt: when frightened, the follicle muscles that hold a feather in place may relax, resulting in easier loss of feathers.
  • Frontal Shield: Extension of the bill onto the forehead.
  • Frugivores: animals that eat fruits.
  • Functional lateralization: the left hemisphere of a bird's brain is dominant, and is associated with learning and innovation in vocalizations.
  • Funnel trap: used to capture birds. It does not have moving parts, but instead has an entrance shaped like a cone that narrows at the end so birds can not exit.
  • Fur Plug: A blanket of fur or "cotton" used to conceal eggs from predators or keep them warm when the female leaves the nest. Common with chickadees for eggs that are not being incubated.

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  • Gape: Base of the bill where the mandible join (rictus.) As a verb, when nestlings (or females being courted) open their beaks to be fed.
  • GCFL: Great crested flycatcher.
  • Genetic monogamy: A single male and single female are the parents of all young in a nesting. See social monogamy.
  • Genotype: Genetic characteristics of an individual that do not vary with circumstances. See phenotype.
  • Genus: a grouping in the classification of living organisms having one or more related and morphologically similar species. In the common binomial nomenclature, the name of an organism is composed of two parts: its genus (always capitalized) and a species modifier. For example, the scientific name for the Western Bluebird is Sialia mexicana. Sialia is the genus, mexicana is the species.
  • Gizzard: a large, strong muscular structure in the esophagus used primarily for grinding and digesting tough food. The avian equivalent of molars. Less muscular in birds that eat softer foods like insects or fruit. Also sometimes called the ventriculus, crop or craw, although actually it is found AFTER the crop and proventriculus.
  • Glabrous: having no hairs, projections, or pubescence; smooth (as in mealworms)
  • Gleaning: peering and poking to obtain food (e.g., examining cracks in bark.)
  • Gonys: Lowermost ridge on lower mandible.
  • Gourd: The fruit of plants in the family Cucurbitaceae, with a hard shell. When properly dried, then can be used as a birdhouse, but can not be monitored or cleaned out. Plastic and ceramic gourds are used for Purple Martin houses.
  • Granivorous: feeding on seeds or grain. E.g., House Sparrows are primarily granivorous. Also graminivorous?
  • Granulated: ( as in eggs): surface is rough, almost like it has sand stuck on it
  • Grit: Some birds (e.g., barn and Tree Swallows) eat little pieces of sand or stone (insoluble) to aid with grinding up and digesting seed hulls and insect exoskeletons. It is stored in the crop/ventriculus. Crushed oyster shells (soluble grit) can be offered mainly to provide a source of calcium.
  • Ground foraging: walking around on the ground to look for food.
  • Ground sallying: dropping to eh ground briefly from a nearby perch for food.
  • Ground trap: A trap used to catch House Sparrows and starlings that is placed on the ground or elevated. Different from an inbox or nestbox trap.
  • Growth bar: One light band plus an adjacent dark band on a tail feather. It denotes 24 hours growth.
  • Guano: Large deposits of bird feces.
  • Gynandromorph: half male, half female. Results when the fertilized egg first divides, and the sex chromosomes separate abnormally, with ZW (female) chromosomes on one side, and ZZ (male genotype) on the other side. Does not occur in mammals because hormones override the genetic differences on the right and left sides.

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  • Habitat:the place or environment where a plant or animal naturally or normally lives and grows.
  • Hack: to rear a young bird by hand and then release it into the wild while providing food until they become independent. Only permitted wildlife rehabbers are allowed to raise birds protected by the Migratory Bird Treaty Act. Sometimes unsuccessful in species where the birds need intensive tutoring from parents to learn how to be independent.
  • Hallux: The large, opposable single rear toe on a bird's foot that helps a bird grip a branch. Bluebirds have three front-pointing digits, and one or hallux.
  • Haematophagous: blood sucking, like a blow fly, nest mite, black fly, mosquito, etc.
  • Hanger strap: a metal strap (e.g. 16 gauge steel x 12" x 1.5") used to mount a nestbox on a pole. It is attached to the back of a nestbox, and then the other side is bent and inserted into conduit or PVC pipe.
  • Hantavirus: Hantavirus Four Corners (also known as Muerto Canyon) virus causes a rare but deadly pulmonary syndrome. The virus is transmitted by infected rodents through urine, droppings, or saliva.
  • Hardiboard: fiber cement siding. Sometimes used to make nestboxes, but a special saw is needed to cut it.
  • Hardware cloth: Tough, stiff but bendable wire mesh that comes in a roll. Somewhat flexible. Available in hardware/garden stores.
  • Hatch: A baby bird breaks through the egg and is 'born.' Also refers to emerging from a pupa or chrysalis.
  • Hatching: the moment an organism emerges from an egg, pupa, or chrysalis.
  • Hatching success: Number of eggs that hatch (compare to fledging)
  • Hatchling: a newly hatched bird.
  • Hawking or Sallying: flying from a perch to capture flying insects, like Mountain Bluebirds.
  • Head cocking: turning the head to the right or left to get a better view.
  • Head down: When bird approaches another species and assumes motionless posture with head bowed down, feathers of nape and crown raised. May be an invitation to preen, as in Cowbirds.
  • Head stripes: bold lines on the head.
  • Head Scratch: Many birds scratch their heads with their feet.
  • Helicopter Monitors: Bluebird landlords who hover over nestboxes, micromanaging. Excessive intereference may short circuit learning by individuals and evolution of the species.
  • Helpers: Non-parents who aid in rearing young. More.
  • Hen: female bird. Usually used for gallinaceous birds like chickens. Opposite of cock.
  • Heterogametic sex: Unlike mammals, female birds have two different sex chromosomes - Z and W.
  • Heterospecific: between two different species (opposite of conspecific), as in cooperative breeding between bluebirds and swallows.
  • Hibernation: winter dormancy in animals characterized by a significant decrease in metabolism.
  • Hindhead: Back part of the crown. Occiput.
  • Hindneck: back of the neck (nape/collar)
  • Hippoboscid flies: flat "louse flies" (genus Ornithomyia) that live among bird feathers and suck blood.
  • Hive tool: a metal tool used by bee keepers. Comes in handy for squashing paper wasps and cleaning out boxes.
  • Hobby wire: Fine gauge, flexible wire that can be used in place of monofilament to deter House Sparrows from nestboxes or feeders. Also used on a Magic Halo. 28-30 gauge for model airplanes works well.
  • Hole Hog: When an older nestling crowds the nestbox entrance hole trying to snag all the food proffered by parents (a made up word).
  • Hole guard: Sometimes called a Squirrel tooth-bender or hole protector. Placed around the entrance hole to a nestbox to prevent squirrels or woodpeckers from enlarging the hole. Often made out of metal. Different size holes can also be use to exclude larger birds (called a hole restrictor).
  • Home range: area that an animal uses during the course of its daily activities - may not be defended like a territory.
  • Hole restrictor: See hole guard.
  • HOME: Hooded merganser.
  • Homeothermic: having a body temperature that is constant and largely independent of the temperature of its surroundings; an endotherm.
  • Home range: Area occupied and defended during nonbreeding season vs. territory used (and defended) for mating and nesting. Varies by species and also depends on habitat (e.g., food abundance.)
  • HOSP: (English) House Sparrow.
  • Host: The organism from which a parasite obtains nourishment and shelter.
  • Hover or Hover foraging: Flying somewhat stationary in midair (like a helicopter) while rapidly beating wings. Mountain Bluebirds hover while hunting and then drop to the ground.
  • HOWR: House Wren.
  • Huber trap: An inbox trap designed by Joe Huber that uses a flat plate of steel attached to a trip rod.
  • Humeral tract (feathers): extends from where the leading edge of the wing meets the body over the dorsal surface to the trailing edge of the wing
  • Hutchings "Coon" Guard: a PVC tube placed over the entrance hole to deter raccoons and cats. More info and instructions.
  • Human commensals: characterized by a symbiotic relationship in which one species benefits while the other is unaffected. E.g., House Sparrow, European Tree Sparrow, which live closely associated wtih humans (which provide a source of food and places to nest)
  • HY: hatch year - the time from hatching until the following nesting/breeding season, somewhat less than 12 months.
  • Hybrid: The offspring of parents of two different species. Hybrids can be extremely variable - even siblings within a single brood can look quite different from each other. Most hybrid species are fertile.
  • Hyoid (apparatus): A long complex of bones (e.g., in Downy Woodpeckers) with two horns or forks that extend backward from the base of the tongue into the skull.
  • Hyperphagic: eating a lot, as in fattening up in late summer before migrating.
  • Hyperthermia: heat stroke which occurs when the body produces or absorbs more heat than it can dissipate, body temperature climbs uncontrollably. Can result in death.
  • Hypomelanism: See Albino.
  • Hypothermia: when the core body temperature has dropped to significantly below normal and normal metabolism begins to be impaired. Common cause of nestling death during extended periods of cold, rainy weather.

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  • Immature: a young bird that is not fully adult (not being cared for by the parents, but not old enough to breed.) For bird banding, a young bird capable of sustained flight known to have hatched during the same calendar year in which it was banded.
  • Imprinting: learning occurring at a particular age or a particular life stage that is rapid and apparently independent of the consequences of behavior. It typically involves an animal or person learning the characteristics of some stimulus, which is therefore said to be "imprinted" onto the subject. E.g., a rescued nestling may become imprinted onto a wildlife rehabilitator.
  • Incubation (period): The period during which the adult bird starts sitting on eggs to warm them until they hatch. In some species, the male brings the female food while she is incubating. Incubation is not continuous - birds occasionally leave the nest to defecate, etc. Depending on the species, may be the female only (as in bluebirds) or both male and female (as in House Sparrows.)
  • Incubation patch: see Brood patch.
  • Indeterminate (egg laying). When a species can be induced to continue laying by daily egg removal or to lay fewer eggs when extra eggs are added to the nest during laying. Also see determinate. More.
  • Infanticide (al behavior): Adult kills babies (not for food), an uncommon behavior in birds. House Sparrows and House Wrens will kill babies of other species, Tree Swallows will kill babies of other Tree Swallows which is called intraspecific infanticide (see Dead TRES)
  • Infant exploitation: cannibalism (where the adult eats an infant of the same species)
  • Infertile: For a bird, sterile - unable to reproduce (e.g. sperm are not alive.) For an egg, has not been fertilized.
  • Infundibulum: the first section of the oviduct, where fertilization of the egg occurs.
  • Insectivore: An organism that eats insects.
  • Insectivorous: eats insects, e.g., Tree Swallows.
  • Insert or Inbox Trap: fits in a nestbox, behind the entrance hole, and trips when a bird enters the box.
  • Intergrading: merging of characteristics of two populations wher their ranges overlap. May indicate that they should be treated as a single species.
  • Interference Competition: An individual's activities prevent use of a resource by other individuals. Also see Exploitative Competition. An example is HOSP destroying nests of other birds.
  • Internal compass: how organisms figure out what direction to go in long-distance movements like migration - hypothesized.
  • Internal pipping: See pipping.
  • Interspecific: Between different species.
  • Intraspecific: Within members of the same species, as in competition for a nest site.
  • Introduced: alien species, brought either intentionally or accidentally by humans to an area. Not native. Sometimes invasive.
  • Invasive species: a non-native (i.e., introduced or exotic) organism like a plant or animal capable of establishing a breeding population in the new location without further intervention by humans, and becomes a pest in the new location, threatening the local biodiversity.
  • Invertebrate: lacking as spinal column.
  • Iridescence: Rainbow-like multi-colored play of light on feathers - e.g., on the back of a Tree Swallow.
  • Iris: colored part of the eye, surrounding the darker pupil. It controls the amount of light that enters the eye.
  • Irrupt or irruption (invasion): to undergo a sudden upsurge in numbers, especially when natural ecological balances and checks are disturbed (e.g., when winter food is in short supply.) In birds, refers to unusually large numbers of non-migratory birds moving out of their typical nesting range.
  • Isthmus: where inner and outer membranes of the albumen (egg white) are added in the female.
  • IUCN: International Union for Conservation of Nature - a network of members and more than 1000 governmetn and NGO member organizations and volunteer scientists.

  • Jailhouse feeder: A feeder with metal or wooden dowels (looks like prison cell bars) on the sides to allow entry only to smaller birds.
  • Jewel wasp: Nasonia vitripennis, a beneficial insect that wasp drills a small hole into the blow fly pupal and deposits an egg. The wasp larva then consumes the larva.
  • Joint nesting: social polygyny where one male nests with 2 females that use the same cavity.
  • Jugulum: front of the neck (foreneck, throat, throat patch).
  • Julian date (JD): a continuous count of days and fractions since noon (sometimes used to count how many days till egg laying.) Compute.
  • Jumper: A Purple Martin nestling that falls out of the nest prematurely, perhaps to escape heat or parasites.
  • Juvenal plumage: Feathers on a juvenile bird after down feathers are lost.
  • Juvenile: In birds, young that are not sexually mature. They may have different plumage or markings than adults.
  • Juvenile dispersal: movement of a young bird from the site where it hatches to the site where it breeds

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  • Landlord: The person who supplies nesting houses to birds and successfully hosts them.
  • Lard: Lard is an animal fat produced from the fatty or otherwise unusable parts of pig carcasses. It can be used to make suet.
  • Larva: (pl. larvae) the immature, wingless, and often worm-like stage of a metamorphic insect that hatches from the egg, alters chiefly in size while passing through several molts, and is finally transformed into a pupa or chrysalis from which the adult emerges. The larva can look completely different from the adult form (e.g., blow fly)
  • Latin name: the scientific name. E.g., Sialia sialis is the latin name for Eastern Bluebird. Usually in italic font.
  • Leading edge (of wing): front edge of wing in flight.
  • Leucistic plumage: See Albino. Plumage is dilute, paler/whitish overall, with a faint pattern (leucism). This is more scarce than a partial albino. More.
  • Lice: Parasites that live in the birds feathers. There are more than 150 species, including chewing lice, louse flies and feather mites.
  • Lifter pole: A device used to take down hanging/high nestboxes and replace them.
  • Listserv: An email forum for sharing information - Cornell sponsors the Bluebird_Listserv. Threads are archived by topic.
  • Live trap: A device that traps creatures but does not kill them - e.g., an inbox trap.
  • Local extinction: see Extirpated.
  • Lore: The region between the eye and bill on the side of a bird's head, used for ID.
  • Lower mandible: lower part of bill.
  • Lyme disease: a potentially serious illness transmitted by deer ticks.

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  • Magic Halo: A patented metal hoop with/without hanging lines, used on top of feeders to deter House Sparrows.
  • Magnum: The section of the oviduct where albumen is added to the egg.
  • Maintenance of a trail: Repairing, replacing, etc. nestboxes to ensure that the contents are adequately protected from the elements, etc. For example, includes replacing a cracked, leaking roof.
  • Malar Streak: area on the sides of the chin. Whisker/mustache.
  • Management of a trail: Monitoring boxes regularly, and maintaining the nestboxes.
  • Mandible: see Beak. The lower portion of the bill, or lower mandible. The upper mandible, or maxilla, is a flattened, hollow bony cone reinforced by bony struts called trabeculae.
  • Mantle: feathers on the upper surface of the wings and center of the back.
  • Mast: edible seed and fruit produced by trees or shrubs that wildlife species will consume - hard (e.g., acorn) or soft (e.g., Flowering dogwood fruit.)
  • Mate Guarding: The male stays close to female (especially fertile females), probably to ensure that young are theirs (i.e., to prevent extra pair breeding attempts.)
  • Maxilla: upper portion of the bill or upper mandible.
  • Mealworm: The larval form of Tenebrio molitor, or the darkling beetle.
  • Mealworm farm: a set up to grow mealworms, from egg to beetle.
  • Median Line: stripe through the crown.
  • Melanism or Melanistic: Caused by an excess of dark (brown or black) pigments. Can be caused by a genetic mutaion or sometimes diet. Some species have a naturally occuring melanic form or "morph." Less frequent than albinism or leucism, and may occur in combination with partial albinism.
  • Metabolism: chemical processes occurring within a living cell or organism that are necessary to maintain life. In metabolism, substances are broken down to yield energy, or synthesized.
  • Metal Conduit: Pipe used for electrical wiring, also used for mounting nestboxes.
  • Microhabitat: Parts of a broader habitat type that are used by an individual during the course of its daily activities.
  • Micromanagement: in monitoring, checking a nestbox too often (e.g. hourly) or interfering unnecessarily with the nesting process.
  • Millet: group of small-seeded genera of the grass family (Poaceae) widely grown around the world for food or animal feed. Proso millet (Panicum miliaceum) is often included in inexpensive bird seed mixtures.
  • Migrant: an animal that makes seasonal trips between breeding and wintering areas. Opposite of resident.
  • Migration: regular, extensive, seasonal movements of birds between their breeding regions and their wintering regions. Not all birds migrate - e.g., Black-capped Chickadees do not. Sometimes migration is moving between elevations (between mountains and adjacent lowlands) as in Western Bluebirds.
  • Migratory Bird Treaty Act: A 1918 federal law that made it illegal to hunt, capture, ill possess, sip or sell migratory birds, nests and eggs. It does not extend to House Sparrows or starlings.
  • Mist net: a mesh net used to capture wild birds for banding or other research projects.
  • Mite: a tiny arachnid (related to spiders, thus having 8 legs) parasite that may live in the nest, nostrils, trachea, lungs, and air sacs of birds, or feathers.
  • Mixed Clutch: Two different species in one nest (e.g., Tree Swallow and Eastern Bluebird per Chapman 1955 - more info.)
  • Mixed Species Flock: a group of birds from different species, such as chickadees flocking with nuthatches and and woodpeckers.
  • Mobbing: When birds gang up on another species to harass and drive away predators or intruders- e.g., Tree Swallows driving off a bluebird or House Sparrow or a human, often while making harsh vocalizations.
  • MOBL: Mountain Bluebird.
  • MOCH: Mountain chickadee.
  • Molting: The process of dropping old feathers and growing new ones in their place. Most birds molt at least once a year, often in late summer. Also see prebasic molt.
  • Monitoring: checking a nestbox to gather data and address problems. The goal is to increase the likelihood of successful fledging. May or may not be considered to include maintenance of nestboxes. More.
  • Monofilament: Fishing line, used to deter House Sparrows from nestboxes or feeders.
  • Monogamy: mating with only one member of the opposite sex at a time, i.e., one male mates with one female in an exclusive pair bond.
  • Monomorphic: having a single form. Opposite of polymorphic.
  • Morph or Phase: A naturally occuring melanistic form. This plumage variation is distinctive in certain species, and is retained throughout the bird's life. It is not related to age or sex.
  • Morphology: physical attributes of an individual.
  • Mortality Rate: Number of birds dying in a defined time period (usually 12 mos.) divided by the number alive at the beginning of the period. Complement to Survival Rate.
  • Mounting: Putting up a nestbox (e.g., on a pole, tree, etc.)
  • Moustache: area at the sides of the chin. Whisker/malar streak.
  • Mud nesters: Birds like Barn and Cliff Swallows that build nests out of mud.
  • Multi-holed box: A nestbox with more than one entrance hole, designed to improve ventilation, attractiveness, or escape options.
  • Murmuration: A flock of European starlings (can number a million or more)
  • Mycoplasmal conjunctivitis: An eye disease that strikes House Finches.
  • Myth: a commonly held inaccurate belief that is not based on fact.

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  • NABS: North American Bluebird Society.
  • Nape: back of the bird's neck.
  • Nares: nostrils.
  • Nasofrontal hinge: The part of the beak located between the bill and skull.
  • Natal: relating to birth (e.g., natal nestbox - where bird was born)
  • Natal dispersal: Movement away from where a bird is born to where it breeds.
  • Natal down: The fluffy feathers on hatchlings. They get pushed out by incoming juvenal pennaceous feathers in the first few weeks. A few wisps may remain attached to the incoming feathers (e.g. on the head.)
  • Natal philopatry: Tendency of young to come back to the area where they were born. See delayed dispersal
  • Native: naturally occurring, indigenous or endemic (i.e., not introduced, either accidentally or on purpose).
  • Natural selection: the predictable predominance of individual organisms with advantageous traits, like camouflage or agility.
  • Neophobia: fear of novel objects. May be a factor with HOSP fear of sparrow spookers, magic halos and monofilament.
  • Neotropics: Region that includes southern Mexico, Central America, Caribbean, and South America.
  • Neossoptiles: Natal down feathers (e.g. on Tree Swallows)
  • Nest Attempt: When a bird attempts to reproduce, usually only counting when at least one egg is laid.
  • Nestbox: A birdhouse where cavity-nesters build a nest. Some people write this as two words (nest box.)
  • Nestcam: A video camera used for viewing activities inside a nestbox. Also called a nestbox camera.
  • Nest change: Replacing a nest that is wet, or infested with blow flies etc.
  • Nest cup: With regard to construction, the interior part of the nest where eggs are laid. In some nests (e.g., House Wren) the interior cup is of different construction.
  • Nestling: for bird banding, a bird incapable of sustained flight.
  • Nesting success: the number of nesting attempts that succeed in fledging at least one nestling.
  • Nest site fidelity: when a bird returns to a nest site used the previous season or from which it fledged.
  • Nest site showing: Early in breeding season, male shows female a cavity (clings to outside, looks inside repeatedly).
  • Nestling: A baby bird still in the nest.
  • NestWatch - Cornell Lab of Ornithology database on nesting birds (including cavity nesters.) Replaced TBN (The Birdhouse Network)
  • New World: Western Hemisphere (including North and South America)
  • Niche: in ecology, the position occupied by an organism or group of organisms) within an ecosystem or the conditions making possible a habitat.
  • Nicititans: a third eyelid (as in Downy Woodpeckers) that helps protect the eyes by partially covering it and brushing the surface with tears to remove particles.
  • Nidicolous: staying in the nest until grown/nearly grown, or sharing a nest with another species (e.g., mites in a bird nest).
  • Nidifugous: Precocial young leaving the nest soon after hatching - e.g., Wood Ducks.
  • Nit: the egg of a louse or other parasitic insect. Looks like a tiny, white capsule. When they are on the head area, the bird cannot pick them off.
  • Nocturnal: Of, relating to, occurring or active at night - e.g., flying squirrels.
  • Nocturnal hypothermia: lowering body temperature (e.g., 10-15 degrees F) during cold winter nights to conserve energy (e.g., chickadees, Downy Woodpeckers)
  • Noel Guard: a rectangular tube of hardware cloth stapled to the front of a nestbox to keep predators out, but allow the users of the nestbox in and out. More info and instructions.
  • Nocturnal Hypothermia: lowering of body temperature by about 10-15 degrees to conserve energy on cold nights. Metabolism (e.g., heart rate and respiration) also slow down.
  • NOFL: Northern flicker.
  • Nomadism: a population that shifts from site to site between seasons in a relatively unpredicable manner - may not happen every year.
  • Nomenclature: a system of naming and categorizing objects in a given category - e.g., Linnaeus's system of binary names for birds - made up of the genus and species.
  • Nostrils: or nares. The paired external openings birds breath through, located on their beaks.
  • Nyjer: a narrow, small black seed enjoyed by goldfinches, pine siskins, house and purple finches. Not preferred by House Sparrows. Also called thistle seed (although it does not come from the thistle plant), niger or nyger seed.

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  • OATI: Oak titmouse.
  • Obligate: required, exhibited by all species without exception.
  • Obligate brood parasite: Birds that can not build their own nest, and instead pawn their eggs and young off to a host of another species. The only North American birds in this category are the Brown-headed and Bronzed cowbirds.
  • Occiput: rear of the crown, hindhead.
  • Oesophagus: the first part of the throat. A muscular tube that draws the bird's food further into its body.
  • Oil gland: A small organ located above the tail at the base of the rump on most birds. Also called a uropygial gland or preen gland. Birds used their bill to press oil from the gland and then spread it over their feathers for insulation, waterproofing, feather pliability and health.
  • Old World: Eastern Hemisphere (including Africa, Eurasia, Australia)
  • Omnivore: eats pretty much anything, not selective.
  • Oology: the study of eggs.
  • Orbital ring: The frelshy ring around the eye; contrasting color in some species.
  • Order: A taxonomic groping or lineage. Birds are divided into 30 orders, all of which end in "-formes."
  • Orientation, entrance hole: The compass direction that a nestbox entrance faces.
  • Ornithology: The science of studying birds - The branch of zoology that deals with the study of birds, including their physiology, classification, ecology, and behavior.
  • Ornithologist: A scientist practicing ornithology (e.g., researching, managing or teaching).
  • Ossification: The natural process of bone formation which also provides the basis for skulling birds to separate hatching year from older birds.
  • Oval: (egg shape) - the shape of a chicken egg, rounded and largest on one end, tapering distinctly towards the narrower end. Sometimes called "ovate."
  • Ovate: (egg shape) oval.
  • Oviduct: The passage along which eggs travel.
  • Oviparous: animals that lay eggs, with little or no other development within the mother. All birds are oviparous.
  • Ovulation: when the ovary releases an egg (usually every 24 hours), which then moves into the oviduct.

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  • Pair bond: the association between two birds who have come together for reproduction; can be short-term (lasting only through egg-laying or the rearing of young) or lifelong.
  • Pairing: Putting nestboxes 5-25 feet apart (or even back to back), usually to provide nesting for both bluebirds and Tree Swallows. Note that BRAW considers boxes within 100 feet of each other to be paired.
  • Pamprodactyl feet: all four toes directed outward, as in some swifts. Also see Zygodactyl and Anisodactyl feet.
  • Pancreas: part of the digestive system, which may compensate for lack of chewing. It produces carbohydrate, fat and protein-digesting enzymes.
  • Panhandling: a fledgling begging the adult of another species for food. More info.
  • Paper wasp: The native paper wasp (Polistes fuscatus) is smaller than the European paper wasp, brown, and lacks vivid yellow markings. They tend to only be aggressive when defending their nests, and are otherwise beneficial insects to have around the garden.
  • Parabolic reflector: Device shaped like a saucer used to gather, magnify and focus sounds to make high quality recordings.
  • Paraffin: canning wax, used to coat the inside roof and upper walls of a nestbox to prevent paper wasps from nesting.
  • Parasite: An organism that lives in or on another organism, the "host," at whose expense it obtains nourishment and shelter. An example is a blow fly. Also see ectoparasite and endoparasite.
  • Parasite load: the amount or quantity of parasites possessed by an individual that may affect the individual’s capacity for survival.
  • Parental provocation: When the parents entice the young to fledge (as in bluebirds, not seen in House Finches.)
  • Partial albinism: See Albino. (I prefer the term leucism or pied/piebald.) More common than true albinos, have a pied appearance and usually have irregular patches/groups of pure white feathers - e.g., the head may be entirely white. After an injury, feathers that regrow may lack pigments. Note that some birds also develop stray white feathers as they age. Also see True Albino and Leucism. More.
  • Partial migrant: Within populations, some individuals migrate and some take up winter residency near or on breeding sites. (BNA)
  • Partial molt: replacing only some of the body's feather tracts.
  • Partial Paternity: Some, but not all offspring are genetically related to one male.
  • Partners in Flight: conservation project focusing on native North American birds. Collaboration between state and federal land managemetn agencies and nongovernmental conservation groups.
  • Passenger hypothesis: Suggests that exotic species may expand into areas where other birds are not already using resources, perhaps because of habitat degradation or disease. Contract to "driver hypothesis." (From Birdscope Spring 2007)
  • Passerine: Of the order Passeriformes, a songbird.
  • Passive control: With regard to House Sparrows, control methods that do not kill eggs or adults. Includes methods to deter House Sparrows from coming to feeders. Also includes wing trimming.
  • Paternity: parenthood (genetically.) May be partial (some offspring), complete (all offspring) or zero.
  • Pecking or Tapping: method of foraging, driving bill into a substrate (like bark) but not penetrating it very deeply to find insects/larvae.
  • Peck-dominance: Who gets to eat first. In a winter flock of titmice and chickadees, the chickadees are socially dominant at a feeder.
  • Pectinate: having tooth-like projections on toes or the middle claw (e.g., Barn Owl)
  • Pellet: Undigestible remains (exoskeletons, feathers, bones, fur) regurgitated by owls, raptors etc. Ornithologists often study them to determine what birds have been eating.
  • Penultimate: next to the last, as in the penultimate egg. Some birds like Tree Swallows start to incubate after laying the penultimate egg.
  • Perch: on a nestbox, a peg below the entrance hole. Not recommended for bluebird houses because it may help House Sparrows take over a nestbox.
  • Persistent layer: Will continue to lay eggs if lost/removed - e.g., 28 eggs were collected in one Red-headed Woodpecker cavity, after which the pair drilled a new hole in the same tree and raised four young.
  • Permanent Resident: A species that breeds and winters in the same region, e.g., House Sparrows and Chickadees. This gives them an advantage over migrating birds.
  • Pesticide: a chemical, or sometimes biological agent such as a virus or bacteria, used to control, to repel, to attract, or to kill pests including insects, weeds, birds, mammals, fish, and microbes, that compete with humans for food, destroy property, spread disease, or are considered a nuisance. Pesticides are usually, but not always, poisons. They include bactericides; herbicides, which kill or prevent the development of weeds; fungicides, which kill fungi; plant growth regulators, which prevent excess growth of a plant; virucides; insecticides, which kill (or prevent the development of) insects; acaricides or miticides , which kill mites; avicides, which kill birds; chemosterilants; molluscicides, which kill snails and other mollusks; nematicides, which kill roundworms; rodenticides, which kill rodents, generally mice or rats. They may also include repellents and attractants for insects, birds and mammals. Humans have used pesticides since before 500 BC.
  • Phase or Morph: A naturally occuring melanistic form. This plumage variation is distinctive in certain species, and is retained throughout the bird's life. It is not related to age or sex.
  • Phenology: the study of cyclic biological events as a function of environmental change (e.g. climate change)
  • Phenotype: physical characteristics that may change in an individual in response to environmental factors.
  • Philopatry: faithfulness to a region or an area for breeding (near where they fledged.)
  • Phylogeny: the tree of genealogical relationships among species that provides a foundation for taxonomic classification.
  • Piciformes: The taxonomic order for woodpeckers.
  • Pied or Piebald: Of two or more colors in blotches. Having irregular or isolated white patches (symmetrical or asymmetrical - as in the entire head on a Bald Eagle.) More.
  • Pinfeathers: New growing feathers encased in a horny sheath during the early stages of a molt.
  • Pip: See pipping.
  • Pipe flange: rim or collar on a wheel or pipe which holds it in place, gives it strength or allows it to attach to another object. Water pipe can be coupled to the bottom of a nestbox with a pipe flange plate. The center has a threaded hole that the water pipe screws into. Can also be used to attach a nestbox to a conduit pole, using a conduit connector.
  • Pipping: When the embryo starts to break through the shell to hatch. Internal pipping happens when the embryo uses its egg tooth to break through the membrane that separates it from the air bubble. External pipping happens when the bird breaks through the eggshell to the outside world.
  • Piracy: Stealing food or nesting material from another bird. Nestling and fledging martins may enter neighboring nest compartments to steal food from their host's parents.
  • Pishing: Attracting birds by making precise hisses, whistles, chips and squeals.
  • Play: Behavior usually associated with honing/practicing or preparing for adult activities like hunting or dominance contests essential to survival. Tree Swallows often drop and re-catch feathers used to build nests. A captive raven may "play" with stuffed animals (tossing them in the air, placing them in a nest, and eviscerating them.)
  • Plumage: the covering of feathers on a bird. It may change (e.g., in color) over different seasons (e.g., breeding plumage may be more colorful.)
  • Plumulaceous: downy (as in feathers)
  • Pneumatization: When the skull gradually divides into two layers, separated by a space. Happens in the first autumn of a birds' life. ""Skulling" can be used to determine a birds' age.
  • Pole pounder: A device used to push a pole into the ground.
  • Polyandry: One female mates with two or more males. Also see Polygyny and Polygamy.
  • Polygamy: Both polygyny and polyandry occur. Pairing with more than one mate at a time (kind of like a harem concept.)
  • Polygyny: One male mates with several females. Also see Polyandry and Polygamy.
  • Polymorphism: Species occur in a variety of plumage colors that have no relation to age or sex.
  • Prebasic Molt: Replacement of feathers (molt) that occurs in juveniles produce their first winter adult plumage
  • Precocial: chicks that (e.g., ducklings) have their eyes open at hatching, are covered with down, and leave the nest very soon after hatching to find food for themselves. Opposite of altricial.
  • Predator: An animal or other organism that hunts and kills other organisms for food. For example, a raccoon is a predator that eats eggs and nestlings.
  • Predator guard: a device placed underneath a nestbox (e.g., a baffle on a mounting pole) or on the entrance hole to prevent predators such as snakes and raccoons from raiding nests.
  • Preen: cleaning, grooming, and maintaining parts of the body. Birds regularly preen feathers to remove parasites, keep them in good aerodynamic condition, and "oil" them with waxy, oily secretions that come out of the uropygial (preen) gland.
  • Preen gland: the uropygial gland located on the rump at the base of the tail that produces oily waxes, fatty acids, fat and water to keep feathers moist and flexible, and possibly to protect them from bacteria and fungi. Looks kind of like a tick.
  • Premature fledging: when leave a nest under their own power, accidentally, earlier than expected. Often they can not fly well and are thus more susceptible to predators and bad weather. With Purple Martins, may occur because nest compartments are too hot or infested with parasites. More info.
  • Pressure treated lumber: Wood treated with chemicals to make it last. Not suitable for nestbox construction because of potential impact on bird health.
  • Prey: animal eaten by a predator.
  • Prey Preparation: Parents (e.g., Mountain Chickadees) may remove heads, wings, appendages before feeding to nestlings, especially when they are very young.
  • Primaries: are the long flight feathers of the wings which are attached to the manus, or the "hand" part of the wing. The number of primary feathers varies from 9 to 11, and are numbered from the innermost primary to the outermost.
  • Primary cavity-nester: Nests in a hole and can create its own cavity (e.g., a woodpecker with a strong beak). This does not mean that they may not utilize an existing cavity (e.g., flickers will use nestboxes.)
  • Primary coverts: feathers that cover the base of the primaries on the upper surface of the wing.
  • Prolactin: a hormone that promotes development of a brood patch and stimulates incubation and brooding.
  • Promiscuity: Males and females mate more or less indiscriminately. See Polyandry Polygamy and Polygamy.
  • Prospecting: Juvenile and adult birds inspecting nesting sites during the fall migration period. More.
  • Protoporphyrin: is a pigment that produces colors ranging from yellow and pink to reddish buffs or browns. It is one of three pigments secreted by cells in the oviduct (see biliverdin).
  • Proventriculus: A bird's stomach has two parts - the anterior portion (proventriculus) and the gizzard (posterior portion.) The proventriculus is a glandular stomach that is a tube-like area that produces digestive juices (e.g., enzymes like pepsin and hydrochloric acid.)
  • Proximal: nearer to the central portion of the body
  • PROW: Prothonotary warbler.
  • Psilopaedic feather coat: a few scattered down feathers found on hatchlings of many cavity nesters (unlike the dense fuzzy covering [ptilopaedic] on ducklings.) Those feathers usually only last a week or two.
  • Psittacosis: also known as parrot disease, parrot fever, and ornithosis, an infectious disease caused by a bacterium called Chlamydophila psittaci that can be contracted from parrots, macaws, cockatiels and parakeets, pigeons, sparrows, ducks, chickens, etc. After an incubation period of 5-14 days, symptoms can mimic severe atypical pneumonia with flu-like symptoms like fever, chills, headache, muscle aches, and a dry cough.
  • Pterylae: feather tracts separated by apteria.
  • Pupa (plural pupae): The non-feeding stage between the larva and adult in the metamorphosis of holometabolous insects, during which the larva typically undergoes complete transformation within a protective cocoon or hardened case.
  • PUMA: Purple martin.
  • Putative parent: believed or supposed to be the parent
  • PVC: polyvinyl chloride, a hard plastic used to make drainage pipes etc. Used to make tube nestboxes, or sometimes to manufacture regular shaped nestboxes.
  • Pygostyle: supports tail feathers for braking and steering.
  • Pyriform: egg shape with larger end distinctly blunt and rounded, tapering to a narrower point on the other end, pear-shaped.

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  • Rachis: The part of the feather shaft that supports the vanes.
  • Race: Subspecies.
  • Range: geographical area within which a species normally can be found
  • Rank: status relative to other birds
  • Rare: population density is always low in a species, either in a particular area or generally. Globally, a species that is locally common within a very small range.
  • RBNU: Red-breasted nuthatch.
  • Rebar: a steel reinforcing bar. Can be driven into the ground, and then a conduit pipe is placed over it for nestbox mounting.
  • Recovery Rate: for bird banding, the proportion of banded birds recovered and reported to Bird Banding offices.
  • Recurved: Curved upward or backward (as in a deformed bill.)
  • Rehabilitate: To treat a wild animal (including birds) for an ailment or injury. A special wildlife rehabilitation permit is required.
  • Remiges: the flight feathers of a wing - stiff and large.
  • Replacement clutch: eggs laid to replace a clutch in which none of the eggs hatched.
  • Rehabber: See wildlife rehabilitation.
  • Re-nest or Renest : Starting another nest and laying a replacement clutch after the failure of a first nest attempt. Some birds like Purple Martins may renest in the same nest; chickadees usually move to another location.
  • Repeating Trap: a ground trap that doesn't need to be reset to catch another bird. Some use an elevator mechanism.
  • Resident: a species that passes the winter (overwinters) successfully in most years. Also see Sedentary.
  • Retreating: When a submissive birds avoids another bird.
  • Retrices: long flight feathers in the tail, used for steering and braking.
  • Rhamphotheca: A horny sheath that covers both jaws of a birds' beak.
  • Rictal Bristles: stiffened, hair-like feathers near bill, on the cornars of the mouth (rictus). Function may be to protect the bird's eyes from insect legs and wings, or it may have a tactile function like whiskers on a cat.
  • Rictus: based of bill where the mandibles join. Gape.
  • Ringing: see Banding
  • Riparian: along banks of rivers and streams.
  • Roost: (n) - a place, or support on which birds rest; also a group of birds resting together. (v) - to settle down for rest of sleep. More.
  • Roost box: like a nestbox, only designed for roosting. The hole may be at the bottom to retain warmth, and it may have a larger interior with perches inside. More.
  • Rounded: spherical - short elliptical (as in an egg shape)
  • Rump: Area between the uppertail coverts and the back (butt).
  • Runt: the smallest nestling. Sometimes the result of asynchronous hatching.
  • Runt egg: Noticeably smaller than the smallest extreme expected by normal variation within a clutch. May be different in shape (e.g., more narrow.) More.

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  • Sedentary: Nonmigratory - generally birds that do not move long distances in dispersal or other movmeents. See Resident.
  • Saucer-shaped nest: Shallow cup with the height of the rim not more than 2x the diameter of the eggs.
  • Sally: see Hawk
  • Saturation: With regard to bird population, when a habitat has reached it's carrying capacity, or ability to support that creature. With regard to nestboxes, when the maximum number of nestboxes that will be used are available in a certain habitat.??
  • Scaling: searching for prey by using bills to remove small pieces of bark (e.g., Downy Woodpeckers.)
  • Scapulars: Area of feathers between the back and the wings.
  • Scatterhoarding: hiding food in bark crevices and under leaves, moss, or lichen. Retrieval of food items is accidental, not memory-based. Opposite of caching.
  • Schizochroism: ?one pigment overlays another on the same feather. Also see albino.
  • Scientific name: the technical name of a creature, made up of the genus, species, and sometimes a variation. E.g., the scientific name for the Western Bluebird is Sialia mexicana. Scientific names are usually used to avoid confusion because common names may vary by region. Birds also have standard English names.
  • Scout: In Purple Martins, the first arrivals at a breeding site.
  • Seasonal molt: when worn feathers are replaced with new ones, or camouflaging colors are replaced with brighter colors. Also see Molt.
  • Secondaries: the long flight feathers of the wing arising from the ulna, or "forearm" region of the wing. Secondary feathers are nearer the bird's body than the primary feathers, and are numbered from the outermost feather to the innermost. There are six on most birds.
  • Secondary cavity-nester: Nests in cavities, but is unable to excavate its own hole (e.g., a bluebird, because it does not have a strong enough beak.)
  • Semiplumes: in between down and contour feathers, with a large rachis and loose downy vanes. They enhance insulation.
  • Set: total number of eggs laid by a female bird in one nest attempt. Also called a clutch.
  • Sexing nestlings: determining whether nestlings are male or female. By day 13, bright blue feathers protruding from wing sheaths indicate a male.
  • Sexually dichromatic: the male and female differ in coloration - e.g., Eastern Bluebirds, Downy Woodpeckers.
  • Sexual dimorphism: differences (e.g., color, markings, size) that occur between the sexes of a given species. For example, Eastern Bluebirds exhibit sexual color dimorphism as there is some difference in plumage color between males and females that allows us to distinguish the sexes.
  • Sexual maturity: Age at which a species is physiologically capable of breeding and raising young. For many small cavity nesters, this may be at 9-12 months of age.
  • Sexual selection: traits that affect ability to attract a mate (e.g., bright colors) that are preferred and thus are selected for over time in the process of evolution
  • Shared nesting: When two females of the same or different species lay their eggs in the same nest and share incubation and subsequent family duties. The two females will either sit side by side or one on top of the other to incubate the eggs. In some instances they will take turns incubating the eggs. Also see brood parasitism.
  • Sheath: the outermost layer of cells that fall off when feather growth is complete.
  • Shell membranes: tough and fibrous, mostly protein, inside the egg shell.
  • Shell (egg): the outer layer of the egg, which is mostly calcium carbonate. If there is any pigment, it is laid down in the spongy layer of the shell.
  • Shoulder: feathers overlying bases of median secondary coverts.
  • SREH: Starling-resistant Entrance Hole. Used in Purple Martin houses.
  • Shrub: Multi-stemmed woody plant (e.g., no distinct single trunk).
  • Sialia: The genus for bluebirds (scientific name.) Pronounced cee-AL-ee-a.
  • Sialis: The species for Eastern Bluebird (Sialia sialis, scientific name). Pronounced cee-AL-iss.
  • Siblicide: nestmates kill a sibling, sometimes when there is not enough food for all chicks.
  • Sidling: a behavior that usually occurs near a nest, where the owner (e.g., a starling) moves or hops along a branch or wire (without facing the intruder), forcing it to move away.
  • Single Brooded: Having one clutch or family per breeding season. Tree Swallows are typically single-brooded.
  • Site Fidelity: Returning to the same nest site in subsequent breeding seasons.
  • Skulling: looking for pneumatization to determine a birds' age, in order to separte hatching year birds from older birds, based on the degree of ossification of the skull. The feathers on the crown are moistened and moved apart, to view the skull through the nearly transparent skin. If the skull is pink, the bird is young of the year. If it is dullish white, pneumatization is complete so it is an adult or a young-of-the-year bird with cranial separation complete.
  • Siblicide, obligate: When a larger chick kills a smaller sibling, e.g., owls.
  • Sleep: Most common posture is with head turned and resting on back, with bill tucked under shoulder (scapular) feathers. Some birds sleep on tree branches or buildings, some in cavities.
  • Snag: a standing dead tree. Many primary cavity nesters build nest holes or roosts in snags, which are often reused by secondary cavity nesters. More info.
  • Snake Display: When a bird on a nest mimics a snake in a nesting cavity, in the case of a Tufted Titmouse, by hissing while lunging/striking side of nestbox. Mountain Chickadee female or older nestlings may do this. Possibly an anti-predator or general nest protection behavior. See video.
  • Soaring: Sustained flight relying on air currents vs. flapping wings. Tree Swallows soar when feeding on aerial insects.
  • Social Inheritance: when behaviors are 'learned' or passed down in a culture.
  • Socially monogamous: a single male and female form a basic social unit in breeding territory. They cooperate to produce a clutch of eggs and raise young.
  • Social polyandry: one female nesting with more than one male
  • Song: territorial vocalization used to communicate the identity and whereabouts of an individual to other birds and/or to signals sexual intentions and create/maintain pair bonds. Different from call.
  • Songbird: a bird belonging to the suborder Oscines of Passeriformes (about 4000 species) also called passerines, in which the vocal organ can produce various sound notes, commonly known as bird song. Not all songbirds produce melodious tunes - e.g., the House Sparrow. Songbirds all have preen glands with a unique nipple structure, unique sperm, a specialized perching foot with a large hallux, uniquely arranged deep tendons, and simplified foot muscles that facilitate perching.
  • Song (or vocal) repetoire: the distinctive songs produced by a single bird.
  • Sound (egg): An egg with an unbroken shell.
  • Sparrow resistant nestbox: A birdhouse style that may not be preferred by House Sparrows, but may still be used if competition for nest sites is high, or for the purposes of attack. No box invented to date that can be entered by a bluebird is "sparrow-proof" because bluebirds are bigger than House Sparrows.
  • Sparrow Spooker: A device placed on top of a nestbox that scares away House Sparrows.
  • Speciation: the splitting of one phyletic lineage into two or more.
  • Species: a kind of organism subset of genus. Usually defined in ornithology as an interbreeding group of birds that is reproductively isolated from other such groups. See subspecies. Bird species have characteristic sizes, shapes, songs, colors, ecological niches and geographic ranges.
  • Species of Special Concern: category created by the Fish & Wildlife Service and apparently is the Federal Government's version of a 'watch list' for species. States may have their own definitions.
  • Spinal tract (feathers): extends along the mid-dorsal line, and includes the cervical, interscapular, dorsal and pelvic regions
  • Spooker: See sparrow spooker.
  • Spotting scope: A single lens device used to view birds at a distance. Usually requires a tripod.
  • Stereotyped behavior: distinctive behaviors consistently used in a certain situatino, like a courtship display (wing waving by bluebirds.)
  • Stray: an individual found outside that species' regular range. Also called a vagrant.
  • Strigiformes: the taxonomic order for owls.
  • Subadult: a young bird that is sexually mature and capable of breeding but that does not yet exhibit characteristic plumage or marking of an adult of the species. For bird banding, a bird known to have hatched in the year preceding the year of banding.
  • Subelliptical (egg shape): rounded at the ends, but a little more elongated, tapering more towards the ends, with the broadest part nearer one end than the other.
  • Subfamily: subset of a family, wtih one or more genera.
  • Subspecies: geographical subset of a species, wtih different morphology or coloration. May also have different habitat, voice, or other behaviors. Can interbreed. Sometimes called a race.
  • Suborbital ring: eyelids.
  • Subspecies: Definable plumage and/or other physical differences between regional populations of the same species. Presumed to be able to interbreed freely with other members of their species if given the opportunity. Sometimes referred to as "race." Identified by a third name (trinomial nomenclature) after the genus and species (e.g., Sialia sialis grata.) Also see Species.
  • Succession: Sequence of plant communities that occur after disturbance (like clear cutting of trees or farming), and end in the region's dominant habitat type.
  • Suet: For bluebirds, a mixture of lard or vegetable shortening and peanut butter. Other items may be added such as sunflower chips and dried fruit, and whole wheat flour to hold it together.
  • Supplant: When a bird takes over the position of another, by flying, walking or hopping.
  • Summer Resident: Breeds in one areas, but winters elsewhere.
  • Sunbathing or Sunning: May occur on rooftops - e.g., House Sparrows lie on their bellies with wings extended to varying degrees, body feathers fluffed up in a trance-like state. Birds may position their bodies perpendicular to the sun, roll their heads to the side, erect throat feathers, and close eyes. Helps to stay warm, may cause ectoparasites to move making them more accessible for removal, releases Vitamin D from preen oil. More.
  • Superciliary line: Line of feathers above the eye. Supercilium, eyebrow.
  • Superspecies: Group of species that appear to have a relatively recent common ancestor.
  • Superworms: (also called King or sometimes Giant mealworms) are Zophobas morio (sometimes listed as Zoophorbas) They are not treated with hormones, but are naturally larger (around 2-3 times bigger) than regular mealworms.
  • Survival Rate: the number of birds surviving at the end of a defined period of time, divided by the number alive at the beginning of the period. See Mortality Rate.
  • Suspended molt: Molt that stops briefly during a short period like during migration or when food is in short supply, and then resumes.
  • SY: second year - the year after the hatch year. For Purple Martins, considered a subadult.
  • Symbiotic: A prolonged association between two or more different organisms/species that may, but does not necessarily, benefit each member; a relationship of mutal benefit or dependence.
  • Sympatric speciation - genetic variation in species inhabiting the same geographic regions so they become different species.
  • Synanthropic: "Living with man," i.e., in close association with or somewhat dependent on humans (for habitat, food, nesting material, etc.) House Sparrows and Purple Martins are good examples.
  • Synchronous hatching: hatching that occurs at the same time or nearly the same time, usually within one calendar day.
  • Synchronous nesting: nesting by a local population in which breeding pairs initiate egg laying within a relatively short period of time (a few days to a few weeks), as in Tree Swallows.
  • Syrinx: The larynx-equivalent in a bird, where most vocalizations are produced. It is deep in the chest where the trachea (windpipe) splits into two bronchi. The thin membranes vibrate and create sound as air goes by them. Some birds with a more highly developed syrinx can produce a wider range of vocalizations (e.g., Starlings.)
  • Systematics: The systematic classification of organisms and the evolutionary relationships among them based on comparisons of fossils, preserved specimens, behavior and DNA; taxonomy.

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  • T-post: A metal fence post with little ridges on it to hold wire. Sometimes used for mounting nestboxes.
  • Tallow: is rendered beef or mutton fat (suet). Unlike suet, tallow can be stored for extended periods without refrigeration, provided it is kept in an airtight container to prevent oxidation.
  • Tanglefoot: A sticky barrier prevent crawling insects like ants from getting to a nestbox. Usually placed on tape below a nestbox in a place where the birds can't get into it. Note: Tree Tanglefoot Pest/Insect Barrie is a different product than Tanglefoot Bird Repellant.
  • Tapping: Slower than drumming, when birds strike a substrate while feeding.
  • Tarsometatarsus: a long, single leg element made up foot bones fused fused to one another and to the metarsals, enabling birds to walk on their toes rather than on the whole foot.
  • Tarsus: lower part of the leg between the knee and the foot.
  • Taxon: (plural taxa): unit used in grouping and naming organisms - e.g., family, genus, species.
  • Taxonomy: hierarchical scientific naming of organisms and their classification with reference to their precise position in the animal or plant kingdom. Kingdom>Phyla (e.g., Aves)>Orders>Famiily>Tribe>Genus>Superspecies>Species>Subspecies/Race.
  • TBN: The Birdhouse Network. A citizen-science project of the Cornell Lab of Ornithology in which people place nestboxes in their yard or neighborhood and then monitor the birds that nest inside. Changed to Nestwatch.
  • TBT: Transcontinental Bluebird Trail. A continent-wide grassroots conservation
    effort to help the bluebirds and other native, cavity-nesting bird species. NABS maintains a database of nestboxes and nesting results.
  • Thermoregulate(ion): maintaining a constant body temperature.
  • Temporary nestbox: A mobile nestbox with an insert trap used to capture House Sparrows or starlings.
  • Terminal Encounter: An encounter of a dead bird or a bird band that is no longer on the bird
  • Territory: a defined, defended area (including land and waters) where an animal resides, usually considered to be a possession of an animal. E.g., even the communal Purple Martin often defends several adjacent nest compartments with a common porch in a martin house. Also the home range used (and defended) for feeding, mating and nesting.
  • Territorial: an organism which defends an area against intrusion (usually from members of its own species).
  • Tertiaries: Flight feathers (closest to the body) on the wing that adjoin the secondaries.
  • Thermoregulate: Ability to control body temperature - e.g., in Tree Swallow nestlings when they are 9.5 days old. Birds do not have dermal sweat glands that secrete perspiration. On hot days they may gape or pant in an effort to cool off.
  • Thistle: See nyjer.
  • Threatened species: likely to become endangered in the near future in all or a significant part of its range (ESA 1973, States may have their own definitions.)
  • Tibiotarsus: The top of the leg bone - like the human femur.
  • Toehold: a saw kerf or other means (hardware cloth, rough wood) that allows nestlings to grab onto the nestbox wall to fledge.
  • Torpor: Reduced activity and metabolism to save energy, sometimes entered on cool evenings or seasons.
  • Trabeculae: Bony struts in the upper jaw and forehead of a bird. In woodpeckers, trabeculae reinforce the bill and help it withstand pounding.
  • Trail: see bluebird trail.
  • Trap: A cage, usually made out of metal, placed on the ground to trap House Sparrows or starlings. It may have a funnel type entrance, or an elevator that drops down and send the sparrow into the cage. An "insert trap" fits in a nestbox, behind the entrance hole, and trips when a bird enters the box.
  • Traplining or Trap-lining: a type of foraging behavior where a series of locations like trees and snags are visited in a sequential and systematic way (e.g., Downy Woodpeckers.)
  • Treeline: Elevation or latitude above which trees do not grow.
  • Tremble-thrust: Adult stands in cup and thrusts/stabs beak deep into the nest between eggs or nestlings, and vibrates it rapidly and vigorously, perhaps to knock detritus and parasites away from nestlings down to the bottom of the nest/to increase porosity/ventilation and insulation of the nest (described by Hartshorne 1966/Haftorn 1994?)
  • TRES: Tree Swallow
  • Tribe:
  • True Albino: Rare in nature. Usually results from a genetic mutation that interferes with the production of the pigment melanin. All feathers are white. Without protective pigments in eyes, true albinos quickly go blind. Their feathers wear out more quickly since they lack pigments to provide structural support. Also see Partial Albino, Albino and Leucism. More.
  • TUTI: See ETTI.
  • TY: Third Year (bird age)
  • Type I territory: Furnishes all the requisites for breeding - nest and food supply are in the same territory. Tufted Titmice occupy Type I territory.
  • Type II territory: Birds locate the nest within the territory, but go off the territory to obtain food.
  • Tyro: Someone new to bluebirding. Also called a "newbie."

  • Utility pole: a telephone pole. Don't mount boxes on a utility pole without asking permission from the utility first.
  • Undertail coverts: feathers covering the underside of the base of the tail.
  • Universal sparrow trap: An inbox trap designed by Steve Gilbertson that uses a piece of steel tape measure that springs up to block the entrance hole.
  • Upper Mandible: upper part of beak.
  • Uropygial gland: during preening, the bird squeezes small amounts of oily liquid from this organ, located on the upper surface of the tail.
  • Uterus: where the shell is formed on the egg (over a period of about 20 hours in Downy Woodpeckers)

  • Vagrant: an individual found outside that species' regular range. Also called a Stray.
  • Vane: flat part of the feather that comes off the rachis of the shaft - webbing.
  • Van Ert sparrow trap: An inbox trap designed by Floyd Van Ert that uses a steel door and a small coil spring to block a nestbox entrance hole.
  • Vane feathers: The smaller contour feathers that cover the body surface and the larger flight feathers of the wings and tail. OR the interlocking system of barbs and barbules that form the flexible but cohesive surface on a contour feather.
  • Ventilation hole: A hole or slot in the side or front of a nestbox that allows air to circulate through the interior.
  • Ventral tract (feathers): includes cervical, sternal and abdominal regions
  • Ventriculus: See gizzard.
  • VGSW: Violet-green swallow.
  • Vix bit: a special drill bit used to center screw holes on hinges.

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  • Watchlist: species that are declining or have limited ranges, but are not yet threatened or endangered may be placed on a list by conservation organizations like the National Audubon Society or Partners in Flight.
  • WBNU: White-breasted nuthatch.
  • Weaving action: rapidly moving the head and whole body from side to side on the tip of the tail as a pivot, with the neck stretched out and bill pointed on a line with the body, and the whole body elongated. Wings and tail are not spread. (e.g., Downy Woodpecker)
  • WEBL: Western Bluebird.
  • Whisper Song: Male House Wren sings without opening its bill and song is inaudible from >10 m. It coincides with period when pairs are copulating - maybe to avoid attracting other males to a fertile female.
  • White (egg): Several layers of albumen inside the egg - clear in an undeveloped egg.
  • Whole mount: Bird mounted in a lifelike pose, with glass eyes. Compare to bird skin.
  • Wildlife rehabilitator: An individual (usually licensed) that takes injured/orphan wildlife and restores them to health, ideally so they can be released into the wild.
  • Window strike: A bird colliding with a pane of glass because it doesn't see it, or is trying to defend its territory from its own reflection. Can result in death.
  • Wing: A modified forelimb used almost solely for flight.
  • Wing bars: Pale or lighter colored bars on a wing, formed by the tips or bases of greater and median secondary covertss.
  • Wingspread/Wingspan: the distance from tip to tip of the longest primary feathers of the outstretched wings.
  • Wing rustling: noise made by wings (e.g., Downy Woodpeckers may do it when disturbed by a potential predator or when approaching their nest.)
  • Wing quivering: Rapid open and closing or vibrating of wings, usually with body in a horizontal position. Occurs during courtship feeding when female begs male, or when juveniles beg for food from parents, sometimes (e.g., in Mountain Chickadees) when an intruder comes into territory. Both adult male and female Tufted Titmice wing quiver.
  • Wing-spreading or Wing-threat: a display to signal aggression, where both wings are spread and the tail is spread. White-breasted Nuthatches may sway during the wing-threat, Downies may hop towards the intruder.
  • Wing trimming: Cutting the primary and secondary flight feathers on a wing which reduces the birds ability to fly. A passive control measure used for House Sparrows.
  • Wing wave: or wing flicking. While perched, a male bluebird flaps, one wing in a circular motion, usually to attract a mate. May fan tail and warble or chatter. In starlings, wing flicking can be a threatening display.
  • Wing Whull or Wing Ruffle: when excited, Downies and Red-cockaded woodpeckers may fly with wings stiffly held, producing a whull-like sound.
  • Winterizing: Insulating or closing up ventilation holes to maintain interior temperatures in a nestbox that may be used for roosting.
  • Wintering Grounds: Where migrating birds go after summer breeding season ends. For example, Purple Martins migrate to the tropics of South America.
  • Wishbone: The furcula, which compresses and rebounds like a powerful spring in rhythm to the beat of wings.
  • WODU: Wood duck.
  • Woodland: Habitat dominated by trees, but with a more open canopy than a ture forest.
  • Worn plumage: Older plumage that looks frayed, ragged, colorless or paler than regular plumage.

  • Xanthochroism: an unusual pigment condition, where birds have yellowish or orange plumage instead of red. If it is caused by diet (as in the case of House Finches) it is not xanthochroism.

  • Yolk (egg): The yellow part of the egg. it consists of the latebra, germinal disc, concentric rings of yolk material and the vitelline (colorless) membrane that surrounds and contains the yolk.

  • Zero Paternity: When males are not the father of any of their paired mates offspring.
  • Zygodactyl feet: Three forward toes and one rear toe - as in most woodpeckers, owls and some swifts. See Anisodactyl feet.

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Acknowledgements to Primary Sources:


All bluebirders must feel like "one of the chosen ones" when we are fortunate enough to have nesting bluebirds on our own property....
- Lillian Lund, Sialia, 1984


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