Western scrub-jay funerals: cacophonous aggregations in response to dead conspecifics.

[David Morris]

http://www.npr.org/blogs/13.7/2012/09/06/160535236/do-birds-hold-funerals

Scientists already knew that some corvids — crows and ravens — make
alarm-call vocalizations when they discover the body of another bird.
Iglesias et al. wanted to carry out an experimental (rather than only
observational) study using a corvid species. So they trained
scrub-jays to show up at a feeder at certain times, and then tested
the birds' responses to certain situations.

For instance, they presented the birds with a novel object made of
wood, approximating the form of a dead scrub-jay, and some days later
presented them instead with the actual skins (plus feathers) of dead
jays. The birds never called or formed cacophonous aggregations in
response to the wood object, but they always called at the skins, and
almost always these callings escalated into noisy gatherings.