Don't Be Fooled By Feather Position

Birds are capable of being quite plastic in appearance. Their shape and posture vary greatly in response to an assortment of external influences. In addition to the presence of predator, or a human intruder, various weather factors (rain, wind, and cold) cause birds to assume postures or fly in a manner that seem atypical. One under-appreciated variable that often affects how birds appear to us is  feather position. When alarmed or threatened, most birds raise their head feathers--particularly those on the crown--effectively changing their head shape. This is particularly true with passerines. If you think about it, we often encounter small birds at comparatively close range, surprising them in the process. In addition to changing the general shape of a bird's head, the raising and flattening of head feathers can also affect how large or small its bill looks and modify the color and intensity of its head pattern. Erect head feathers tend to make a bird's bill look shorter and slimmer, while flattened or relaxed head feathers produce the opposite effect. The images below capture some of the variability described above.

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This Savannah Sparrow, photographed west of Eugene, Oregon on 23 April 2009 shows multiple characteristics of a bird on high alert. Notice both the very upright posture and the raised crown feathers, which create an angular head shape reminiscent of a skylark. It also displays a striking face pattern.

Eugene042309

Here is the same Savannah Sparrow just a few seconds later. It had moved to a position a bit farther away from me where it apparently felt a bit more secure. Its posture is less outstretched and upright and the crown feathers have returned to a more relaxed position. Notice that the crown not only looks flatter and more rounded, but it also looks paler brown and the white central crown stripe is less apparent. Also note that the overall pattern of the face is less striking, particular black malar stripe (borders the side of the white throat area) which does not look as black or as flared-out at the bottom.

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For most birders, a small-billed sparrow with an angular crown and a spiked crest (like the one pictured above) comes to mind when they think of a Lincoln's Sparrow. Generally secretive, Lincoln's Sparrows are most often viewed when they have responded to our pishing, so they are already alarmed. This bird popped up at the edge of a wet meadow near Box Canyon in the Cascade Mtns. of eastern Lane County, Oregon on 17 June 2008. It did so in response to my Northern Pygmy-Owl imitations.


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The flat crown and fairly large-looking bill would likely send many birders scrambling for a field guide. While the crown and bill profile are more suggestive of a sparrow in the Ammodramus genus, this is a Lincoln's Sparrow just the same. It was photographed near Fern Ridge Reservoir, west of Eugene, Oregon on 4 October 2008.

Birds also fluff up their body feathers, most often in an effort to create greater insulation from cold when temperatures drop. In some cases this results in an almost comical appearance. Check out the "Sta-Puff" Golden-crowned Sparrow below.

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Most of you probably didn't know that Golden-crowned Sparrow could hybridize with cottonballs. This image was captured at Ridgefield N.W.R. in southwest Washington on 12 December 2008. It was a relatively warm sunny day when this picture was taken. Perhaps this bird was practicing up for the anticipated cold snap that hit this region two days later. On 14 December 2008 local temperatures dropped into the high teens.

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This Golden-crowned Sparrow, photographed at my backyard feeder in Eugene, Oregon on 25 December 2008, sports the more expected shape of this species.

While shape and apparent structural differences typically provide us with good clues to the identity of the birds we see, on occasion they assume postures or hold their feathers in positions that dramatically alter their appearance, rendering them unfamiliar to us. Basing an identification mostly on the apparent shape of a bird can be dicey and may lead to some rather embarrassing misidentifications. When you are looking at a bird that seems strange, take note of its behavior and how it might be responding to weather, the presence of a predator, or maybe even you. By doing this you can often sidestep such pitfalls.

All photographs taken by David Irons

1

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