Look for tail shape and pattern to identify warblers high overhead
Published: March 1, 2008
All birdwatchers look forward to spring, the season when so many birds return from the south in their brightest plumage, singing and displaying to impress potential mates. Spring is also when trees flower and leaves emerge. The bounty of insects, tender young leaves, and flowers draws many of the returning birds to the very tops of trees.
TALES TAILS TELL: On the female warblers above, body sizes and shapes and especially tail shapes and patterns vary, but overall colors are similar.
Art by David Allen Sibley
Spring, therefore, is the time for looking at birds in the treetops, an activity that can lead to frustration.
First, there's the discomfort of looking straight up with binoculars balanced on your eye sockets (leading to the malady known as warbler neck). Then there's the fact that when you do spot a bird, all you can see is its underside, from throat to tail, and the bird is usually back-lit. The traditional field marks that the guides emphasize - face patterns, wingbars, colors, etc. - become hidden, and species that you would never consider "similar" when seen from other angles become challenging to tell apart.
The birds are still readily identifiable. Telling them apart just takes a different approach - a different set of clues. You will need to go beyond the traditional field marks and emphasize features like tail shape and pattern, body proportion, general color, and relative size.
In fact, identifying birds in treetops is much like identifying birds in flight. In either situation, plumage characteristics are obscured, but variations in size and body shape are plain. The difference between the hefty, streamlined body of a Blackpoll Warbler and the rounded body and slender tail of a Black-throated Green Warbler, for example, is obvious.
If you were going to focus on one part of a bird that you saw from below, the best place to look would be the tail, because its shape and pattern provide some of the best identification clues. In fact, tail features will allow you to identify a few species immediately (American Redstart and Magnolia Warbler, for example, and others as you gain experience).
More often, tail shape and pattern will help you reduce the number of candidates to a manageable few. If you see a bird with a mostly white undertail, for instance, you'll know it's one of a few species that can then be sorted out easily by proportions or plumage colors.
David Allen Sibley is the author of The Sibley Guide to Birds, Sibley's Birding Basics, and Sibley guides to birds of eastern and western North America.|
Read more by David Allen Sibley.