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

Great Links and Resources

Adapted from the list posted by Chris (GandiC) on the Web Bluebirding Forum. I am always verifying and adding to the information on this page.

TABLE OF CONTENTS (Click on a link to go directly to that section)

General Bluebirding Resources


Predators and Parasites: WHAT HAPPENED?


Spring and Summer "Bluebirding"

Fall & Winter "Bluebirding"

Hazards for Bluebird Monitors




See North American Bluebird Society Fact Sheets



  • Bluebirding Forum - Garden web discussion forum - mostly backyard bluebirders, some very experienced people and great photographers. Anyone can read, must register to post. No emails - just the website, sorted by threads. Does occasionally have annoying pop-up ads (hit "refresh" to end them.)
  • Bluebird Nut Cafe - discussion forum. Discussion of active House Sparrow management allowed. A little difficult to navigate. Very supportive, great photos posted. Registration optional.
  • Bluebird_L Mailing List - DISCONTINUED IN MAY 2010
    • See new Yahoo Bluebird Monitors Forum - Yahoo password required to post. This is the closest thing to the Bluebird_L. You can browse online or subscribe and post (receiving individual emails or a daily digest) - see more info and instructions. This is the forum I ( check in on most regularly.
    • Bluebird_L archived postings, sorted by topic - NO LONGER ONLINE
    • Bluebird_L Facebook site with wall, discussions. Good for chatting and posting photos. Not moderated. Must register with Facebook to post.
  • CAbluebirds_L - California Bluebird Recovery Group - Yahoo Group for all CA bluebird monitors
  • Nestwatch (Cornell) - how to monitor and collect data - free to join, has code of conduct, discussion forum, resources; and one way listserv on nest-box monitoring, cavity-nesting birds.
  • Some State Bluebird Societies also host forums.
  • North American Bluebird Society (NABS) hotline (phone or email) for questions. NABS also has a Facebook page where you can post photos and ask questions.


The following bluebird societies have websites (there are others that are not online ). Check out the North American Bluebird Society (NABs) site for a complete listing of NABS affiliates (not all the organizations listed below are affiliates). Acronyms shown are not used by all these organizations. Some also have Facebook pages. Some of these organizations collect data on nestbox results (e.g., number of eggs laid, birds fledged, etc.) as does NestWatch, a database maintained by the Cornell Lab of Ornithology.











12-18 days
13-14 days
13-14 days
13-16 days
12-19 days (17-18 typical)
17-22 days +/-
18-24 days +/-
16-24 days
1 1/2" to
1 9/16"
1 9/16"
1 1/2" with rounded edges to
1 9/16" (better**)
1 1/2"
100 yards minimum
(125-150 may be better)
200-300 yards
100 yards.
(200-300 yards may be better)
25 feet + or pair
Breeding Biology

Incubation usually starts the day the last egg is laid. A baby blue's eyes usually open on or about day 8. See timetable and photos showing variations at different ages. Tree Swallow babies are similar.

*NABS recommendations for distance between boxes. Bluebirds may nest closer to each other if foraging habitat is good, cavities are plentiful and/or they cannot see the other pair from their nest site because something (like a building) blocks their view. Brice Prairie Conservation has had good results spacing boxes 200 yards apart. Boxes can also be paired (typically 5-20 feet apart.)

**Mountain Bluebird and Western Bluebird ranges overlap in some areas, and Mountain's need a 1 9/16" hole. Some Western's are larger than others. So the 1 9/16" hole is a safe bet, and will also exclude almost all starlings.


See Monitoring Nestboxes. A bluebird landlord should be prepared before opening the nestbox to check on a nesting, in order to deal with predators, parasites, wet nests, etc. It's helpful to have the following with you:

  • a deep bucket (e.g., cat litter or spackle buckets)
  • several plastic bags (one to line the bucket into which to sit the wet or infested nest with the nestlings; one into which to scrape out the nestbox)
  • an old egg turner (to lift the nest for examining under it and to scrape out the bottom of the box) - if the center of the egg turner is open space, it is easier to check the bottom of the nest itself
  • soft dry grass (in case a replacement nest needs made)
  • trimmed, white craft feathers (in case a Tree Swallow nest needs replaced)
  • a metal putty knife (to smash wasps if found, and scrape a box clean)
  • a bar of high-fat soap (e.g., Ivory (bar) soap) or jar of Vaseline (to coat the interior of the roof against wasps)
  • a container of antibacterial wipes (until hands can be washed)

In areas prone to mice nesting in boxes, also bring:

  • disposable gloves
  • a dust mask
  • a spray bottle of 10% bleach solution (to spray the mouse nest before removing it, and to disinfect box interior)


  • EABL sounds like "Cheer, cheerful charmer" or "chir wi" or "chur lee". When repeated several times, the call resembles the words "truly" and "purity."
  • Best recording of EABL on MBS website (should play when link is clicked - may not work in Firefox. May also have to go to Tools and click "play sounds on webpage"). Also see: Quicktime or RealPlayer
  • Mountain and Western Bluebird song at Animal Diversity Web


The Migratory Bird Treaty Act makes it illegal to disturb a nest or eggs of any native bird without a permit. Permits are seldom granted, even for research. There are exceptions for non-native and exotics such as the House Sparrow (Passer domesticus), European Starling (Sturnus vulgaris)/

Under U.S. federal law, House Sparrow nests, eggs, young, and adults may be legally removed or destroyed. State or local laws may vary. Empty House Wren nests (sticks only - no nest cup) can be removed. Do NOT remove Tree Swallow, Tufted Titmouse, or chickadee nests or eggs. 

It is also illegal collect native bird eggs or nests without a permit. It is illegal to trap or kill native non-game adult birds without a permit, even if they are harassing birds in your nestboxes or feeders. In addition, there is an exception in some areas where cowbirds are threatening populations of endangered songbirds.


The two nest identification field guides mentioned above are the best. But, for a quick check this might help: 




All too often, some predator raids a bluebird nestbox. Sometimes we find just an empty nest that had eggs or babies; sometimes there are remains; sometimes destruction. We rarely get to see 'who' the predator was. But sometimes clues are left. Check this chart for hints as to what the predator might have been Problem/Predator ID or Predator Clues. Also see info on various predator guards and their pros and cons.


House Sparrows (or HOSP) are deadly predators of bluebirds and other cavity nesters. House Sparrows will peck eggs, nestlings, and adult bluebirds to death. Do not confuse other song sparrows with House Sparrows - only House Sparrows are a threat.  See HOSP photos (for ID), HOSP Management (passive and active control methods), History, Population, and HOSP attacks webpages on this website.


See HOSP Management for a comprehensive list of passive and active House Sparrow control methods.

House Wrens

The House Wren also preys on bluebird eggs and hatchlings. It is important to understand that of all wrens, only the House Wren is a danger to other cavity nesting birds. House Wrens generally build nests made of twigs - sometimes even on top of a clutch of a different bird's eggs or nestlings. The first step in protecting against House Wrens in bluebird nestboxes is to site the boxes out in the open at least 100 feet away from wooded areas. However, as wrens over-populate their preferred nesting habitats they are known to move out to those open areas and attack bluebird and Tree Swallow habitats. Nestboxes in areas with deciduous trees are usually preferred of chickadees, which also puts them at risk of House Wren attacks. In such instances, maybe - just maybe - a wren guard will be helpful.


Cowbirds do not build their own nests. Instead, they parasitize the nests of other birds by laying their eggs in them. A cowbird egg in a bluebird nest is uncommon, but does occur.

Cowbirds usually toss one egg of the host clutch and lay their egg in its place. Sometimes cowbirds will parasitize the same nest twice. Some host birds will abandon their nests when a cowbird egg shows up in their nest. Many birds raise the cowbird as their own. Sometimes this 'adopted' baby is so big and ravenous compared to the others in the host nest that the other chicks die of starvation. Bluebird landlords can offer mealworms to help host parents cope with the larger cowbird chick. Technically it is illegal to remove cowbird eggs/nestlings without a permit, as they are native birds.

Some reports say a single cowbird female lays between 60-80 eggs each year, others say 11-20. A cowbird egg looks like a House Sparrow egg but is slightly smaller. Bluebird nestlings have a yellow mouth - a cowbird nestling has a deep pink or reddish mouth.

  • Cowbirds: habits, photo of egg (
  • Cowbird Eggs: this information may help determine if a mystery egg in a bluebird nest came from a cowbird.


To control crawling insects after the first egg is laid, try the following:

  • Remove old nests immediately after babies fledge, as detritus and feces may attract ants. Unhatched eggs occasionally break and attract eggs - DO NOT REMOVE UNHATCHED EGGS TOO EARLY though - wait at LEAST 72 hours after the last egg hatched - see more info.
  • Tree Tanglefoot Pest/Insect Barrier - USE WITH CAUTION! FOLLOW INSTRUCTIONS CAREFULLY! Wrap green garden tape around the mounting pole, right under the box, or UNDER the baffle and then apply the Tanglefoot to the tape (put tape on tightly so ants can't crawl under it). More....
  • Dip Q-tips in an ant repellent called "Terro" and staple them to the outside bottom of the box, and tape a few to the pole.
  • Diatomaceous earth under nest, Amdro ant bait placed weekly in a.m. by base of pole. (Spinosad is an organic ant bait.) Make sure ant bait is fresh (one year max) and does not absorb other smells.
  • Grease (automotive or all purpose) is okay, but when the temperatures get hot the grease may run, whereas Tanglefoot will not. Vaseline or a mixture of turpentine and lithium grease may be painted in a 4" wide ring around the mounting pole (directly under the nestbox, or if there is one, under the baffle, to prevent blue feathers from coming into contact.) It will harden in the sun, so reapply twice during nesting season. Dirt/vegetation stuck to grease will allow ants to cross.
  • ? in the household, a small bundle of crushed sage or crushed peppermint leaves deters ants. Try sprinkling a few under the nest?
  • Lift nest with a spatula and generously sprinkle the floor with cinnamon (that you can buy at the Dollar Store.) Ants should be gone in 24 hours.
  • For specifics on fire ant management, see www.extensionorg/fire_ants
  • More information....


Blow fly larvae suck the blood of nestlings. blow fly larvae seem more common when outdoor temperatures are warm, and on my trail near wetlands. Therefore, first nestings may be free of larvae. The adult blow fly lays its eggs in the nesting material. Usually by the time these whitish-gray larvae are clearly visible, they have already done much of their damage. A significant infestation of blow fly larvae (>10 per chick) can be hazardous to baby birds because of the extent of blood loss when other nesting factors (low food supply, extra cold or extra hot, etc.) are extreme, and can delay fledging. SEE MORE INFO AND CONTROL METHODS (e.g., change out an infested nest, make sure nest is dry, clean out box after each fledging.)


More photos and control methods (

Paper wasps are nasty buggers that seem to love to quickly build umbrella shaped nests in nestboxes, baffles, and feeders. If wasps move into a box, the bluebirds will abandon their nest--even if there are eggs or young. There are several techniques to keep paper wasps from building inside nestboxes, or underneath them (e.g. on a Peterson box). Some work better than others, and some work better with native vs. European paper wasps (Polistes dominulus). The introduced European paper wasp is yellow and black like a yellow jacket, and become active in mid-June, with cells facing outward vs. down. It becomes "imprinted" on a nest site, so just destroying the nest doesn't work.) Native brown paper wasps are less aggressive and tend to build nests only on horizontal surfaces. To PREVENT Paper Wasp nest building:

  • rubbing (or applying with an old paintbrush) a very thin layer of Vaseline on the interior ceiling and down sides about 1", then wiping off excess with a paper towel. Wooden boxes will absorb the Vaseline, so reapply several times per season.
  • Rubbing the ceiling and sides with unscented Ivory (bar) soap or Fels Naphtha soap. (If a bird nest is present, you might want to temporarily cover it to keep soap flakes out). You may have to do it several times a year.
  • Rubbing the ceiling and sides with canning, candle stump or crayon wax (e.g., common household paraffin) This may get messy in hot southern areas, and may attract bees. I found it was less effective than Ivory (bar) soap.
  • Spray the interior roof with a natural pyrethrum formulation - works for 2-4 weeks.
  • Spray the interior and the bottoms of Peterson style boxes with pyrethrin-based caged bird spray available at pet stores. NEVER use other insecticides that could kill or harm birds.
  • Stuff crumpled silver foil or paper towels in the indent underneath Peterson boxes.
  • Squashing: A good thing to carry with you when you check on boxes is a spatula (egg turner), paint scraper or a "hive tool". Usually you have to kill the European paper wasps to keep them from returning. It's best to squash in early morning when wasps are less active. You can also wrap a strip of duct tape around your hand, sticky side out and press it against the beginnings of any wasp nest in a box. Bring a sting kit along with you.
  • For more options, click on Paper wasp ID and Control.

On occasion, bumblebees will inhabit a nestbox (in particular in chickadee nests - another reason to remove old nesting material.) One nontoxic approach that might work is spraying the inside of the house with cider vinegar (this kills wasps also). Mint spray may also work. More on bees.


Mites are uncommon in bluebird nests, but are common in Tree Swallows (TRES) nests. Providing TRES with clean feathers for nesting can prevent mite infestations. This is probably unrealistic for large trails. In that case, try replacing the nest; or use a low-level (0.03 - 0.1%) of pyrethrin pesticide, under the nest (as a toxin, this is considered a last resort.) 1/4 teaspoon of all natural food grade (not swimming pool) diatomaceous earth underneath the nest might help - it dries mites out. Put it in a plastic bottle with a very small opening so you can squeeze it out - it comes out in a cloud of dust. If there are nestlings that are too young to move, place your hand or a paper towel over them during dusting.


Cats can jump at least 5 feet high. A large overhanging roof will help deter them for reaching into the box to remove eggs, nestlings and adults. Also see raccoons.


Nestboxes offered in any area that MAY have raccoons should be on baffled poles. See drawings and instructions for a stovepipe or PVC predator guard. Although no baffle is 100% guaranteed, this is a highly effective baffle and very simple to make: inexpensively! Raccoon Baffle. This same baffle is helpful against skunks and opossum as well. When fitted with hardware cloth (or other solid cap), it will also help against squirrels, chipmunks, mice, and rats, as long as those critters cannot otherwise jump to the box. Raccoons have been known to defeat metal cone guards on poles, even those that are 36" in diameter.

Another option is a Noel Guard. I think they should be put up after the first egg is laid to avoid scaring the birds away. Sheet metal on a wooden post or a conical guard will reduce predation somewhat.


Snakes are common of predators on nestboxes. Because some snakes can rise up 3/4 of their own length, they often easily by-pass raccoon baffles. Some snakes are able to slither straight up vertical surfaces without difficulty. Keith Kridler says a rat snake or coach whip snake can stand up two thirds of their body length and reach into a nestbox without touching the pole or guard. Each of these species commonly reach seven feet in length and can reach lengths over 9 feet.

There are some effective pole-mounted snake traps. All are lethal to the snake, unless watched constantly to immediately free the snake. These traps are usually lethal to a regulated snake species. However, most often, adult birds see a snake long before it is at the box (i.e. anywhere near the trap). If there are babies in the box, at the mere sighting of a snake, the adults will make extreme efforts to fledge the nestlings. If the nestlings are of any age past open-eyes they will make every effort to heed the adults' panic call. If they are not old enough, they will fledge prematurely and most often drop right to the ground into the snake's path. Keeping grass well trimmed within a large perimeter of the box might well be the best deterrent for snakes. However, that's piddlin' little protection against a snake. In any area prone to snakes, the monitor should always exercise care when opening a nestbox. To be 'greeted' by a coiled snake is an unnerving experience.  Here are some methods that might work:

  • Small-diameter, smooth poles help, like the 'three minute post': After making sure there are no utilities underground, use a five-pound maul to hammer a five-foot length of steel reinforcement rod ("rebar") half way into the ground. (Rebar is available from any concrete supply company.) Next, slip a five-foot length of half-inch metal electrical conduit over the rebar. The nest box is attached to the conduit with a pair of two-hole, half-inch conduit clamps. (Conduit and clamps are available from any hardware store.) (Wisconsin Natural Resources Magazine)
  • Using 0.5" conduit instead of wood or larger diameter metal poles results in far fewer nests lost to predation. For folks with many nestboxes on trails and a limited budget, more birds were fledged than if metal T-posts or U- posts or wooden posts are used.
  • Polishing and greasing a narrow diameter pole works, too, but only if the pole is regularly cleaned and regreased before the old grease collects dust and/or hardens in the sun enough to allow the snake to crawl over it. It helps to rub the steel poles with fine steel wool. If you gently rub a silk handkerchief down the pipe and it snags on anything every 6", a snake can probably climb it.
  • The 'Kingston Guard' (a stovepipe baffle) stops most snakes (other than rat snakes, which climb along the seam - see photo). It is the standard for predator protection many Bluebird societies.
    • Note that a big ratsnake can navigate around most baffles.
  • A 3' square piece of hardware cloth placed below the nestbox like a Kingston Guard.
  • The 'Krueger Snake Trap' is also effective. Bird netting is both inexpensive and effective, especially when combined with a Kingston baffle. See PLAN. Remove snakes that are caught - they will die, and the parents may abandon the nest if the snake remains. Also, having a snake in there may freak out the parents and result in premature fledging.
  • Trim grass and weeds around poles boxes are mounted on, as snakes like cover.
  • Charged electric fence wire alternated with ground wires surrounding the pole is perhaps the most effective but it is expensive, requires power near the poles, and isn't recommended if there are children around.
  • WHAT DOES NOT WORK: sulphur, naphthalene, rope. No chemical applications have ever been found to be effective in an outdoor setting, despite claims from distributors.

Other resources:


Spiders are sometimes found in nestboxes, and a few are venomous. Look before you reach inside! This information is from Keith Kridler, coauthor of The Bluebird Monitor's Guide to Bluebirds and Other Small Cavity Nesters See info on spider ID and treatment for spider bites.

  • The Brown Recluse spider is very dangerous to humans. They do NOT spin a sticky catch web for prey but prowl around in search of food. They are normally smaller than 1.5" across their legs and body. A single bite from them would kill a small baby bird. Their venom begins to dissolve soft tissue and flesh. Antibiotics are used to stop the wound growth.
  • Black Widow Spiders are commonly found in nestboxes but they spin a very, sort of haphazard strong web of individual fibers that are "sticky" where they connect to the walls or bottom of a box where insects will walk into the base of the web. They prey mostly on crawling insects. Their venom affects the nervous system and will make a human sick, and may be lethal to a small bird. Despite its reputation, it often attempts to escape rather than bite, unless it is guarding an egg mass or if it is cornered and pressed. The Red Widow Spider is now found in Florida, an imported Australian cousin to our Black Widow. The Brown Widow is mottled brownish. All have the characteristic red hourglass shape on their abdomen.
  • A funnel web spider often will use a nestbox. They are not dangerous and their web often plugs up the hole on the nestbox and resembles a dirty gray handkerchief spread outside the nestbox to catch insects falling through the air.
  • Jumping Spiders are quite quite large (thumbnail-size) and look dangerous (almost tarantula) but are apparently harmless to both the birds and humans. They often have a small egg case that is thick and cobweb-like in a box corner or along the edge of the bird's nest.


According to the Bluebird Monitor's Handbook, the incubating female tries to keep the eggs at around 92-95 °F. Sometimes when it's really hot, the females don't sit on the eggs as much, or they fan the eggs with their wings, or the eggs hatch faster.  On the other hand, they may sit on eggs/nestlings more often to draw heat away. If at all possible, the inside of the nestbox should not exceed 100 °F. Some research indicates that if temperatures outside are 100-104 °F, the percentage of eggs that hatch drop, and nestlings under nine days old can die. Wooden boxes apparently get hotter than PVC boxes. Ventilation holes are key. In hot climates, roofs should overhang the sides by at least 2" and 4" in the front. Also see Fawzi Emad's heat shield design and TBN Experiment by D. Shiels. Some people tie small umbrellas on the top of the box for shade. Others make a second 3/4" Styrofoam roof (custom-cut) with push-pin spacers elevating the Styrofoam from regular roof (works like a cooler) - holes are punched in Styrofoam sides to allow tie-on with elastic. Nestboxes should be mounted where they will be shaded in the afternoon, and if possible to where prevailing winds, breezes will blow through from side to side to carry away summer heat.



The highly pathogenic avian influenza (HPAI H5N1) virus has not been found in North America, it is not easily transmitted from birds to people, nor have there been any well-documented cases of transmission between wild birds and humans. So far, transmission is believed to have occurred from people handling infected poultry/poultry products.

It is safe to keep birding, to attract and feed birds in your yard, and to monitor nestboxes. In general, waterfowl and shorebirds seem to be most affected by outbreaks, rather than feeder birds such as songbirds, probably because the virus spreads from one bird to another most easily through water.

As always, to avoid contracting any illness from wild birds, The Cornell Laboratory of Ornithology recommends that you wash your hands thoroughly after handling bird feeders, bird nests, birdbaths, or water contaminated by bird feces. Using disposable gloves or double plastic bags to move a dead bird is a good idea. These precautions will help keep you safe against harmful germs including HPAI H5N1, should it arrive among our nesting birds.

See USGS precautions for those who handle birds.


Deer mice and several other common mouse species can carry Hantavirus Four Corners virus, which causes a rare but deadly pulmonary syndrome. Breathing in airborne particles contaminated with mouse droppings, urine or saliva can cause infection. The onset of HPS begins with a flu-like illness (see more details.) Approximately 60-70% of infected people will die! PRECAUTIONS: Before removing a mouse nest, use a spray bottle to thoroughly soak the nest and box (to control dust) with a 10% bleach solution (water if no bleach is available). After 15-20 minutes, while standing upwind/wearing a mask, use gloves or a plastic bag to remove the nest, and then sweep and scrape out the box. Wash your hands afterwards. Leave the box open for a day to air it out.
CDC Hanta Virus information.


Lyme tick relative to ruler and dime.  Drawing from CDC website.Lyme disease is transmitted by tiny deer ticks. It is found in every state in the continental U.S., and is common in areas frequented by deer or mice, such as tall grass and forests. Protect yourself by wearing long, light colored pants tucked into your socks/boots, and spraying clothing and exposed skin with an insect repellent. See more information on this website about Lyme disease and bluebirding. The CDC website has excellent information on identification, prevention and treatment.


West Nile disease is killing birds. Believed to be spread by bites of infected mosquitoes and bird-to-bird contact, this virus is of concern to the birding world everywhere. People who develop high fever, confusion, muscle weakness or severe headaches should see a doctor right away. Keep up to date on the spread and what can be done. It is not common, resulting in about 111 deaths per year (a little higher than deaths from lightning strikes.) CDC West Nile Virus.


If you find an ill or injured bird (or other critter) it is crucial to the animal's survival that it be given to a licensed wildlife rehabilitator. It is not legal to keep and care for the animal unless you are a licensed rehabilitator. Find your closest rehabber now that handles songbirds - before the emergency occurs. See link below, call your local nature center, a bird specialty store, or your State wildlife agency. Being prepared is especially important. Some rehabbers on these lists have had to close down due to lack of funding, so checking things out before the panic is crucial. More on wildlife rehabbers and emergency bird care.


If a baby bird is clearly orphaned, or a bird is ill or injured, get it to a licensed wildlife rehabber as soon as possible. In the interim, put the orphaned bird in a small box or bowl lined with a soft towel, or a paper towel or coffee filter, cover it lightly with a cloth (this will help it conserve heat and prevent it from becoming even more stressed - darkness calms them down), and keep it warm (e.g., sit the container on a heating pad set on LOW.) Keep it away from people and pets and avoid handling it, which will stress it out even further. Do not put anything in the baby's mouth, or any food or liquid into the container. More info on what to do with an orphaned or injured songbird.


This topic is pretty much covered in all the books and websites. Here are some general reminders.

  • Rain and high humidity cause wood to swell and shrink. In turn, that can cause wood to crack or roughen. Anyone with wooden boxes should routinely check the condition of the entrance hole to be sure cracks that can catch a blue leg) haven't formed or if the surface has become rough (extra wear on blue feathers). These problems should be quickly repaired, or the box-front replaced.
  • If the unfortunate event of a nesting failure, save the nest IF it is in good shape. This nest could come in very handy to replace a wet or infested nest - just don't keep this nest in the house . in case it has bugs.
  • Blues will likely 'appreciate' it if nestboxes and bird feeders aren't mounted in proximity to each other. Even birds that are no harm to blues could distress them just by being close during nesting.
  • Provide fresh water year round.


When the bustle of nesting season passes, "empty nest syndrome" hits landlords like a brick! BUT fear not! There is still lots to do. Clean out boxes to get them ready for spring. You can prepare boxes for winter roosting or put up roost boxes. Fall is a good time to waterproof and repair boxes, and prevent icicles. Collect soft dead dry grass for replacement nests. Feed suet (see recipes.) Fall is also a great time to plant trees, shrubs and vines that produce berries that will attract birds and help them survive the winter. For details and more ideas, see Bluebirds in Autumn.



It is not "necessary" to offer mealworms to bluebirds. However, in times of cold and/or prolonged-wet weather snaps with a nest full of babies or if one of the adult birds is lost during nesting, mealworms can make the difference in the survival of the babies.  It may also help keep bluebirds in your area. It does get expensive though.  Order 5 days ahead of when you need them. See info on raising mealworms, Fawzi Emad's page for tips on how to store mealworms in the frig, and his design for a starling-proof feeder. Also see Sialis tips and DIY feeder instruction. See list of online mealworm SUPPLIERS. I DO NOT RECOMMEND FEEDING DRIED MEALWORMS - gorging on them can dehydrate birds and even kill them according to rehabber Elise Wolfe.


Bluebirds typically don't eat seeds. While bluebirds prefer insects, after much persistence (like a couple of years) they sometimes sample or even gobble up peanut butter mixtures. They may be more likely to try it if it is next to mealworms, or during the winter. In the meantime, these recipes will be adored by woodpeckers, chickadees, titmice, juncos, cardinals, etc. See Recipes (some of which bluebirds are known to eat.)


  • Jailhouse feeder designed by Fawzi Emad to prevent starling entry
  • Feeder sketches by Linda Janilla Peterson
  • Ketcham Supply Corp. - sell green and black coated wire 1.5". Re: minimum quantities:
    "We are happy to work with folks needing minimal amounts of mesh for their private feeder projects. There are usually two widths in stock here, 13 1/2 inch (9 mesh wide) and 24" (16 mesh wide). The 24 inch mesh has a heavier outside wire running the length of the roll for a little extra strength. Your pricing in $1 per square foot on either size roll, so the 13 1/2" is $1.125 per running foot an the 24" is $2. There is a $10 minimum rolling shop and shearing dept. charge. Orders requiring numerous cuts would be of course a little more. You could pick up or we can ship to you FOB New Bedford. Call (508) 997-4787 And we'd be happy to help you out." Bob Ketcham, 111 Myrtle Street New Bedford, Massachusetts 02740








See Q&A on bird banding. The purpose of putting leg-bands on birds is for research on subjects like migration patterns, nest site fidelity, survival, etc. Banding migratory birds is legal only with a permit from the US Fish and Wildlife Service, and there are different permits for songbirds, waterfowl, etc. Permits are difficult to obtain. You need a very specific purpose (e.g., avian research project) to get one. Some states also require a state permit. The major permit holders are educational facilities, state and federal agencies, and Monitoring Avian Productivity and Survivorship (MAPS) stations. If you're interested, find someone in your area (through a Listserv or by contacting the MAPS Institute for Bird Populations) who bands, and offer to assist them, and learn the steps, considerations, and protocols.


Just a few for birds that may use nestboxes. A full list of alpha codes is available here. Another more complete list of 4 letter codes (for English common names) and 6 letter codes (for scientific names) is found at The Institute for Bird Populations.

Commonly used alpha codes for birds names have four letters. Generally, the rule for alpha codes for two word bird names is the first two letters of the first word followed by the first two letters of the second word - thus Eastern Bluebird = EABL, and PUrple MArtin = PUMA. See neat online bird identification guide.

Note that my list is NOT authoritative! Different groups/individuals may use different lists of cavity nesters. It gets complicated for a variety of reasons:

  • how species are divided (some may list subspecies or use different taxonomic classifications) or lumped together (e.g., introduced varieties of lovebirds, parrots and parakeets)
  • how they define cavity (e.g., does it include a hole in a cliff or a chimney?), whether they ALWAYS, sometimes or occasionally use a cavity
  • whether to count non-native (introduced) species like parrots
  • whether to count parasitic birds (like cowbirds which don't build their own nest but will lay an egg in another bird's nest)
  • what geographic area is covered (e.g., United States/North America)
  • how current the list is (e.g., old lists may not have noted that Red-cockaded Woodpeckers will use a nestbox; new non-natives are being introduced)
  • whether the list is evidence based (n confirmed reports/research)

Also see acronyms list and glossary.


  • When there are more than one species of bird with the same letters, they use the first 3 letters of the first word and the first letter only of the second word - thus TRUmpeter Swan = TRUS and Tree Swallow = TRES.
  • Four word bird names use the first letter of first word, first letter of second word, and first two letters of third word. Another exception when all four words have same initials: BTNW = Black-throated Green Warbler, BTYW = Black-throated Gray Warbler.
  • Subspecies: ETTI refers to the subspecies Eastern Tufted Titmouse. You really need to have the bird in hand to get to subspecies. If you just hear the titmouse in the tree or see it at the feeder, it's a TUTI, a regular Tufted Titmouse. If you just hear a flicker, it's a NOFL, a Northern Flicker. If you can see the color on the wings, you can call it a Red- or Yellow-shafted Flicker, RSFL or YSFL.

Click on the alpha code for more info on biology, nesting behavior, nestboxes, etc.

(An asterisk [*] indicates they may use a NESTBOX) Not all bird names and codes may be up to date. (Some are not listed on as using nestboxes)

EABL = Eastern Bluebird *
MOBL = Mountain Bluebird *
WEBL = Western Bluebird *


ACWO = Acorn Woodpecker
AMKE = American Kestrel *
ATFL = Ash-throated Flycatcher *
BADO = Barred Owl
BANO = Barn Owl - also BNOW *
BCCH = Black-capped Chickadee *
BBWD = Black-bellied Whistling Duck *
BCTI = Black-crested titmouse (TX and Mexico) * (not listed on
BEWR = Bewick's wren *
BHCO = Brown-headed cowbird (nest parasite - does not build it's own nest, not listed on
BEWR = Bewick's wren *
BHNU = Brown-headed Nuthatch *
BNOW = Barn Owl - also BANO *
BOCH = Boreal Chickadee *
BUFF = Bufflehead *
BRTI = Bridled titmouse *
BROC = Bronzed Cowbird (nest parasite, not listed on
CACH = Carolina Chickadee *
CARW = Carolina Wren *
CBCH = Chestnut-backed Chickadee *
CHSW = Chimney Swift (nests in chimneys, not listed on
COGO = Common Goldeneye *
COME = Common Merganser *
DOWO = Downy Woodpecker * (roosting)
EASO = Eastern Screech Owl *
EUST = European Starling * (not listed on
ETSP = Eurasian Tree Sparrow * (not listed on
ETTI= see TUTI or BCTI - the ETTI code is no longer in use *
FLOW = Flammulated Owl (not listed on
= Great Crested Flycatcher *
GIFL = Gilded Flicker (not listed on
GRCH = Gray-headed Chickadee (not listed on

HAWO = Hairy Woodpecker * (not listed on
HOME = Hooded Merganser *
HOSP = House Sparrow * (not listed on
HOWR = House Wren *
JUTI = Juniper Titmouse (formerly with Oak Titmouse as Plain Titmouse)
LEWO = Lewis's Woodpecker (not listed on *
LUWA = Lucy's Warbler
MECH = Mexican Chickadee (not listed on
MOCH = Mountain Chickadee *
NOFL = Northern Flicker *
OATI = Oak Titmouse (formerly with Juniper Titmouse as Plain Titmouse) *
PIWO = Pileated Woodpecker
PROW = Prothonotary Warbler *
PUMA = Purple Martin *
PYNU = Pygmy Nuthatch *
RBNU = Red-breasted Nuthatch *
RBWO = Red-bellied Woodpecker (not listed on
RCWO = Red-cockaded Woodpecker (not listed on
RHWO = Red-headed Woodpecker (not listed on
TRES = Tree Swallow *
TUTI = Tufted Titmouse. (Previously referred to as Eastern Tufted Titmouse or ETTI *)
VGSW = Violet-green Swallow *
WBNU = White-breasted Nuthatch *
WESO = Western Screech Owl *
WODU = Wood Duck *

Lilac-crowned Parakeet
Monk Parakeet/Quaker Parrot
Orange-winged Parrot
Rosy-faced Lovebird
White winged Parakeet
Yellow-headed Parrot

Other North American Birds that reportedly MAY nest in cavities

Barrow's Goldeneye
Black-backed Woodpecker
Black Vulture
Boreal Owl*
Brown-crested Flycatcher *
Burrowing Owl (nests in ground)
California Condor
Canary-winged Parakeet
Cliff Swallow (nests in holes in cliffs)
Common Grackle *?
Crested Myna
Ducky-capped Flycatcher
Eared Trogon
Cordilleran Flycatcher
Elegant Trogon
Elf Owl
Ferruginous Pygmy-Owl
Fulvous Whistling-Duck
Gila Woodpecker
Great Gray Owl
Great Horned Owl
Golden-Fronted Woodpecker*

Ivory-billed Woodpecker
Ladder-backed Woodpecker
Lucy's Warbler
Muscovy Duck*
Northern Hawk-Owl
Northern Pygmy Owl
Northern Saw-whet Owl*
Nuttall's Woodpecker
Pacific-slope Flycatcher
Pileated Woodpecker
Red-breasted Merganser
Red-breasted sapsucker
Say's Phoebe
Spotted Owl
Strickland's Woodpecker
Three-toed Woodpecker
Turkey Vulture
Vaux's Swift
Yellow-bellied Sapsucker
Whiskered Screech Owl
White Wagtail
White-headed Woodpecker
Williamson's Sapsucker
North American Birds that nest on PLATFORMS (not true cavity nesters in my opinion)
American Robin
Barn Swallow
Eastern Phoebe
Great Blue Heron
Mourning Dove
Say's Phoebe
Unusual Cases of Birds Nesting in Boxes

According to Nestwatch at Cornell, they have documented a Dark-eyed Junco nesting in a nest box, a Greater Roadrunner using an open-fronted nestbox, and Common Grackles using nestboxes if the entrance hole is large enough!

A lot of information on this page was originally compiled by Chris (GandiC) from Pennsylvania for the Bluebirding Forum.  I have made some modifications and updates. If you experience problems with any of the links on this page, or have other excellent links to suggest, please contact the webmaster.

"...a leisurely flip of the wing carries them along silently with just enough momentum to keep them afloat in the air, and they often sail for a long way, drifting along with open wings."
- Dr. Windsor M. Tyler  

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