It's that time of year... Bird feeders are up, bringing in more birds closer to buildings. Hawks are coming in to the feeders as well. (You are, after all, feeding the birds; hawks are birds too and appreciate the buffet table just as much as the songbirds.) Sunlight is shining from lower and different angles...
This inevitably leads to meetings between said birds and buildings, meetings that usually end up badly for the bird. Even when birds fly away from a window-strike, survival is not guaranteed due to the likelihood of brain injury causing eventual if not immediate death. (Consider all the recent hullabaloo about football players and traumatic brain injury, then imagine the effect of a wee little bird barreling into plate glass...)
But a window-strike death does give one an incredible opportunity to study the miracle that is a bird up close.
Please keep in mind that every native bird species is protected under the Migratory Bird Act; it is technically illegal to even possess so much as a feather of any native avian species. (Pigeons, starlings, house sparrows and domestic fowl, being non-native imports, are not covered under this law. Most parrots and their cousins require state if not federal permits to keep.)
If your domicile is subject to more-than-occasional window-strikes, first consider why. Have you removed window screens? Are your feeders close enough to the house so that birds don't build up too much speed when frightened off the feeder by a predator? Have you taken adequate measures to prevent reflection or physical impact on larger, non-screened expanses of glass? There are any number of preventative measures that may be taken to reduce injury and death caused by windows.
If you do find dead birds below your windows, considering asking your local nature center if they have a salvage permit and if they collect specimens from the public. Our local centers maintain such permits, and send specimens to the Academy of Natural Sciences in Philadelphia. By noting time, date, place and cause of death of the deceased, you can actually contribute to scientific studies and a bird's death need not be in vain.
Red-winged Blackbird, adult female.