We've had a number of dead/dying birds in our yard, and we took them to the local College Museum. They have an excellent bird collection and...
Some times they use the whole carcass for a pretty display, but most of the time they use them for poison info, parasite infestations, age and other migratory info.
But to get the bones clean, they clean off what they can, then put it in with the ants. Its done in about 3 weeks, depending on size. Thats right, they use the ants to render carcasses clean.
I would also try the local humane society. For a nice donation, they might have one for you..