How to Identify Birds Eggs

How to Identify Birds Eggs
Every once in a while, those of us who enjoy spending time in woods and fields come across a solitary bird's egg lying on the ground---or perhaps even a fallen nest full of them. The following covers a few characteristics to key into when studying an egg. For a guide to identify species, seek out an illustrated manual such as "Eyewitness Handbook of Birds' Eggs" by Michael Walters or the Royal Alberta Museum's virtual exhibit (see Resources).


Difficulty: Moderately Easy

Things You’ll Need:
  • Birding field guide, preferably with egg descriptions and pictures
Step 1
Look at the shape of the egg, which can vary substantially between families and species. Bird eggs range from near spheres (as in the case of kingfishers) to the tapered pyriform shapes produced by the common murre, a seabird.
Step 2
Eyeball or measure the egg's size. While larger birds typically produce larger eggs, the ratio isn't always proportional.
Step 3
Pay close attention to the color and pattern of the egg, which demonstrate the greatest variation of egg characteristics. Some species, like owls, lay pure white eggs. Others are a solid pigment of a different hue, like the famous and beautiful blue eggs of the American robin. Still others exhibit a mosaic of multiple colors, often with a mottled pattern to enhance camouflage.
Step 4
Noting the general habitat where you find an egg can provide additional clues as to species: A big oval egg striated with white and brown near a lakeshore might be an osprey's; a similar-looking one a few miles away in the foothills might more likely belong to a golden eagle. Be aware, however, that egg-eating predators, from raccoons to monitor lizards, can tote their prizes far from the source.
Step 5
If you can narrow down a general type of bird that might have produced your found egg, after considering the above characteristics, check a birding guide to determine likely candidates in whatever geographic region you're exploring.

Tips & Warnings

Look for feathers on or near the egg; they can be used in conjunction with egg characteristics to potentially identify the bird itself.
If you've found a bird's nest, consider its properties, as well; some species can be fairly reliably identified from these constructions alone.
Don't tamper with intact nests unless they're obviously abandoned, and certainly don't remove eggs from them.

Article Written By Ethan Schowalter-Hay

Ethan Schowalter-Hay is a writer and naturalist living in Oregon. He has written for the "Observer," the Bureau of Land Management and various online publishers. He holds a Bachelor of Science in wildlife ecology and a graduate certificate in geographic information systems from the University of Wisconsin.

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