Sialis
 
bluebirds

printer friendly page

Relative sizes of eggs that may be found in Eastern Bluebird nestboxes

Relative sizes of Eastern Bluebird, Tree Swallow and House Wren Eggs. Photo by E Zimmerman


EGG SIZES: from smallest to largest

Common Name

Scientific Name

Avg. length (~inches)

Avg. egg size
(mm)

Carolina chickadee Poecile carolinensis 0.58 14.8 x 11.5
Black-capped Chickadee Poecile atricapillus 0.60 15.2 x 12.2
Chestnut-backed Chickadee Poecile rufescens 0.60 15.3 x 12.0
Boreal Chickadee Poecile hudsonicus 0.60 15.3 x 12.3
Brown-headed Nuthatch Sitta pusilla 0.61 15.5 x 12.3
White-breasted Nuthatch      
Mountain Chickadee Poecile gambeli 0.61 15.6 x 12.3
Tufted Titmouse Baeolophus bicolor 0.63 16.0 x 12.2
Bewick's Wren Thryomanes bewickii 0.65 16.4 x 12.7
House Wren (HOWR) Troglodytes aedon 0.65 16.4 x 12.7
Prothonotary Warbler Protonotaria citrea 0.73 18.47 x 14.55
Violet-green Swallow Tachycineta thalassina 0.74 18.7 x 13.1
Tree Swallow (TRES) Tachycineta bicolor 0.74 18.7 x 13.2
House Finch (rare in box) Carpodacus mexicanus 0.74 18.8 x 13.8
Carolina Wren Thryothorus ludovicianus 0.75 19.1 x 14.9
Eurasian Tree Sparrow Passer montanus 0.80 19.50 × 14.21
Eastern Bluebird (EABL) Sialis sialis 0.81 20.7 x 16.3
Brown-headed cowbird Molothrus ater 0.82 20.89 x 28.53
Western Bluebird Sialia mexicana 0.83 21 x 16
Ash-throated Flycatcher Myiarchus cinerascens 0.88 22.4 x 16.5
Great crested Flycatcher Myarchus crinitus 0.89 22.6 x 17.2
House (English) Sparrow Passer domesticus 0.90 22.8 x 15.4
Bronzed Cowbird Molothrus aeneus 0.90 23 x ?
Purple Martin Progne subis 0.97 24.5 x 17.55
European (Common) Starling Sturnus vulgaris 1.15 29.2 x 21.1

Source: Peterson Field Guide of Eastern Birds' Nests and Peterson Field Guide of Western Birds' Nests, by Hal H. Harrison
Tree swallow. Photo by Bet Zimmerman.House sparrow. ChickadeeBewick's Wren. Photo by S.HarrisBluebird. Photo by Bet Zimmerman.
Tufted titmouse. Photo by Bet ZimmermanCarolina wren. Photo by Bet ZimmermanHouse wren. Photo by Bet ZimmermanBewick's Wren. Photo by S.Harris.

EGGS AND NESTS - click here to see larger photos. 
Unfortunately all the photos are not on the same scale.
HOME | Basics | Resources | House Sparrows | House Wrens | Nest/Egg ID | Site Map and Search | Suet Recipes | Tree Swallows | Contact me Bluebird Conservation

May all your blues be birds!

Photo in header by Wendell Long. If you experience problems with the website/find broken links/have suggestions/corrections, please contact me!
The purpose of this site is to share information with anyone interested in bluebird conservation.
Feel free to link to it (preferred as I update content regularly), or use text from it for personal or educational purposes, with a link back to http://www.sialis.org or a citation for the author.
No permission is granted for commercial use.
© Original photographs are copyrighted, and may not be used without the express permission of the photographer. Please honor their copyright protection.
See disclaimer, necessitated by today's sadly litigious world.
Last updated May 16, 2008 . Design by Chimalis.

Chimalis