Male and female Chipping Sparrow are not exactly alike, and when viewing a mated pair the differences are usually clear. Compare the overall impression of “colorfulness” in these two illustrations, with the male (upper image) showing brighter white on eyebrow and throat, brighter and cleaner rufous crown, darker facial markings, cleaner gray breast, and more […]
Distinguishing male and female Chipping Sparrow Read More »
Looking at the different bill shapes of male and female American Avocet reveals other differences. An earlier version of this essay was published in *Birdwatching* magazine in 2022 I often say that I learn new things every time I go birding, and that the opportunities for learning will never end. One of the keys to
On being an active observer, with American Avocets Read More »
To separate Roseate Tern from the other expected species of terns just look at the upper margin of the folded wingtip (the inner edges of the primaries). Only Roseate Tern shows a conspicuous white edge, and it is present in all plumages and easily visible at a distance. Identifying terns is hard. The differences between
Use this one weird trick to identify Roseate Tern Read More »
Summary – A bird in sagebrush habitat showing features of Timberline (taverneri) Brewer’s Sparrow provides an opportunity to review the distinguishing features, and raises questions about range, variation, and taxonomic status. Comparing two subspecies of Brewer’s Sparrow Spizella breweri S. b. breweri often called Sagebrush Brewer’s Sparrow S. b. taverneri known as Timberline Sparrow On
An apparent Timberline Brewer’s Sparrow in sagebrush habitat Read More »
Detailing my new discovery that male and female Eastern Kingbirds are reliably distinguished by head shape – with the male having a more triangular head. This was verified across multiple birds in Montana, but needs further testing and might only work on adults. On a recent trip to Montana (June 2026) a pair of Eastern
Male and female Eastern Kingbirds have different head shapes Read More »
The Sibley Guide to Birds was published in 2000 – twenty-six years ago! I did a lot of touching-up of the original art for the second edition in 2014, but since 2020 most of my new work for the Sibley Birds app and other projects has been digital. I have decided to make some of
Original art from the Sibley Guide to Birds is now available Read More »
Following up on my earlier post about structural differences, here is a discussion about plumage differences between Mangrove and Northern Yellow Warblers. This post focuses on the two populations that are expected in Florida and the Caribbean – Mangrove Yellow Warbler (Greater Antillean group) and Northern Yellow Warbler (Eastern group). Other populations of both species
Identifying Mangrove and Northern Yellow Warblers in Florida and the Caribbean Read More »
The split of Yellow Warbler into two species in 2025 (by Avilist) brings a challenging identification issue into the mainstream. It is possible to identify most by plumage color (more details here), but differences in the shape of body, wings, and bill provide more consistent clues for identification. Northern undertail coverts longer and fuller, which
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 »