The split of Yellow Warbler into two species in 2025 (by eBird) brings a challenging identification issue into the mainstream. It is possible to identify most by plumage color (more details coming soon), but differences in the shape of body, wings, and bill provide more consistent clues for identification. Northern undertail coverts longer and fuller, […]
The two species of Yellow Warbler differ in structure Read More »
Summary: In practice virtually all will be identified presumptively by range. Positive identification depends on careful analysis of details of song (but questions remain about variation in song). Positive identification of silent birds is not possible on current knowledge. The Warbling Vireos were considered a single continent-wide species until 2025, when two species – Eastern
Identification of Eastern and Western Warbling Vireos Read More »
This is a supplement to my post about identification of Warbling Vireos, which covers the basics of distinguishing them by song In 2025 AOS and eBird split Warbling Vireo into two species, named Eastern and Western Warbling Vireo. Differences in song provide the best way to identify the two species, but there is variation, including
Variation in song of Warbling Vireos Read More »
This morning (Oct 13, 2025) my Facebook page was hijacked and is being filled with spam AI videos. I am waiting for Facebook to restore control to me. In the meantime please spread the word to ignore those posts, and check back in a few days. Thanks for your support and patience. Stay healthy and
My Facebook page hijacked Read More »
The spotted thrushes are notoriously difficult to identify. Differences are subtle and subjective, the birds are variable, and it’s often difficult to get a good view of them. On top of that, when we see a thrush it’s usually just that, one bird. It’s difficult to judge subtle comparative differences when there is no direct
Distinguishing Hermit Thrush and Gray-cheeked Thrush Read More »
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 details that seem more reliable, which are summarized in the one page file here (also as a pdf via this link:
Distinguishing Philadelphia and Red-eyed Vireos by song: Is it possible? Read More »
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 distinguish males from females, a little harder to distinguish one-year-old males from older males, and nearly impossible to determine the age of females. As in many
Determining age and sex of Rose-breasted Grosbeaks in spring and summer Read More »
Estimating numbers of birds in flocks is a skill that we use a lot while birding, but something we rarely get to practice. And – it turns out – something we are really not very good at! I’ve put together a course that explains some of the science behind the challenge, offers lots of quizzes
Test your skills at estimating numbers with a new course Read More »
I’ve just posted about 30 original gouache paintings for sale in the shop. Most of these were painted in 2016 for the app Song Sleuth, and show portraits of common birds singing. The rest are from the early 2000s and were painted for the NY Times syndicated newspaper column “Sibley on Birds” that was
New original art for sale in the Sibley Guides shop! Read More »
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 Egret, and while the split won’t have much impact on North American birders I thought it would be helpful to describe the differences. At
Two species of Cattle Egrets? Read More »