On January 24, I did a blog post about a dove that had hit my window while try to escape from a Cooper's hawk. The dove hit the window pretty hard and left this incredible impression on the glass. I wasn't sure if the white substance on the glass was dander or dust.
Today my neighbor, who home schools her children, was reading a story about the American Bittern bird. The Bittern is considered a Powder Down Bird. My neighbor had read my blog post about the dove and called me to tell me about the American Bittern.
I did some Internet research today and sure enough, that is the explanation for the impression on the glass. The dove is also a Powder Down Bird! Mystery solved!
Here is a great explanation I found for this interesting phenomenon:
Doves don’t have an oil or “preen” gland to help with waterproofing their feathers. Instead, they have “powder down” feathers—extremely fine feathers that disintegrate into a dust-like substance. Through preening, the bird coats its feathers with this dust to provide some waterproofing. If you’ve ever seen a window strike by a dove, you may have seen a “ghost bird” on the glass—a tracing of the bird left on the glass by this powder down. If you and the bird are both lucky, that’s the only remnant of the strike you’ll find…
http://sipapu.wordpress.com/birds/wildlife-rehabilitation/suboscine-and-non-passeriformes-species/ Tina Mitchell