Figure 1. Birds fatally wounded after crashing into windows.

(A) Hermit Thrush (Catharus guttatus) fatally wounded after crashing into a window. (B) Feather pile of a Gray Catbird (Dumetella carolinensis) carcass, which resulted from a window collision. Feather piles are produced when decomposers and vertebrate scavengers, such as raccoons (Procyon lotor), remove most soft and bony tissue, and leave behind various feathers (e.g., remiges, nonflight feathers, and rectrices), body parts (e.g., wing, tail, and legs), and soft tissue (e.g., intestines) (Hager, Cosentino & McKay, 2012). Bird identification is possible if species-specific feathers are present. Moreover, feather piles remain detectable by field workers for several days, and thus, provide evidence of collisions (see Results, Scavenger Assessment).