Sibley Guides » Bird Identification

Possible? It might be, but most of the widely published “differences” are too subjective and/or too variable to be of any value. I dug into this a couple of years ago and discovered some deta...

https://www.sibleyguides.com/2024/04/distinguishing-philadelphia-and-red-eyed-vireos-by-song-is-it-possible/

I put together this matrix of variation in breeding plumage Rose-breasted Grosbeaks, showing the differences between each of the four age-sex classes. In this species it’s relatively easy to di...

https://www.sibleyguides.com/2024/04/determining-age-and-sex-of-rose-breasted-grosbeaks-in-spring-and-summer/

The 2023 Clements/eBird taxonomy update has just been announced, and the biggest surprise is that Cattle Egret will now be considered two species! Few people are familiar with variation in Cattle...

https://www.sibleyguides.com/2023/10/two-species-of-cattle-egrets/

In their 2022 checklist supplement the AOS voted to elevate the southwestern populations of Eastern Meadowlark to a full species, with the name Chihuahuan Meadowlark. it’s been recognized as a ...

https://www.sibleyguides.com/2022/09/identification-of-the-newest-meadowlark-chihuahuan/

Common Grackle is a familiar backyard bird almost everywhere east of the Rocky Mountains, and shows some fairly striking regional variation in color. This variation involves mainly the colors of ...

https://www.sibleyguides.com/2022/05/subspecies-of-common-grackle-bronzed-florida-and-purple/

Stejneger’s Scoter is the Siberian counterpart of White-winged Scoter, only recently recognized as a separate species. The two species are very similar in all respects, and only adult males can...

https://www.sibleyguides.com/2022/04/finding-and-identifying-stejnegers-scoter-in-alaska/

I wanted to know if I could find an objective and reliable feature that would allow me to distinguish any elaenia from any empidonax, and it turns out it's the pattern on the folded wing. The pre...

https://www.sibleyguides.com/2022/04/identifying-small-flycatchers-separating-elaenia-and-empidonax-by-wing-pattern/

For North American birders the most consequential change in the 2021 AOS Checklist supplement is the split of Mew Gull into two species – Short-billed Gull and Common Gull. For most birders thi...

https://www.sibleyguides.com/2021/07/mew-gull-is-now-two-species-how-to-identify-common-gull-and-short-billed-gull/

Prompted by a couple of recent records of Cave Swallows in the northeastern US, I’ve taken a fresh look at subspecies and done some new illustrations. In April 2021 Cave Swallows have been foun...

https://www.sibleyguides.com/2021/04/new-illustrations-of-cave-swallow-subspecies/

Mid-March is when the first northbound Fox Sparrows show up in Massachusetts, and it’s always a pleasure to see this burly, richly-colored sparrow. I’ve been working on some new illustrations...

https://www.sibleyguides.com/2021/03/variation-in-eastern-fox-sparrows/