July 2018 Natural Mystery Answered

It looks like folks know their feathers! We received correct answers to our July Natural Mystery from from everyone who responded, including Lars Roe, Kirsten Welge and Rob Grunewald. These are indeed tail feathers from an American Robin, which may have been killed by an avian predator.

Several of you made use of the US Fish & Wildlife Service's amazing online Feather Atlas in identifying these, and one of you also used Featherbase. Some used these online resources for confirmation, while others used them as a primary research tool.

Kirsten Welge starts us off, sharing her research process:

I started searching through Scott & McFarland’s “Bird Feathers”… and came up empty. Armed with the more comprehensive online atlas, I searched for black, gray, and brown, as well as unpatterned, dual color and white tip on the atlas, and cross-referenced each possibility against range maps from the Cornell Ornithology Lab site.

After looking at Wood Thrush, Rose-Breasted Grosbeak, Lark Sparrow, Eastern Towhee and Red-winged Blackbird, Kirsten honed in on American Robin, noting:

Feather size is the closest match so far, though the patterning of the notch is not quite right. The shape of the feather tips look closer to the mystery feathers than the Eastern Towhee.

Others of you were less detailed about your approach, but made some helpful observations. Rob Grunewald noted both that these feathers have an "S" shape characteristic of the tail feathers on some passerines; and also that "some Robin tail feathers have a white tip which gives them the flash of white in flight."

The only thing that tripped a few people up was the side of the body. As with wing feathers, the narrower vane on tail feathers is the leading edge. These feathers all come from the left side of the tail.

Thanks to everyone who sent in answers, and especially to Kirsten for sharing her process in such detail.