When Western scrub jays summon others to screech over the body of a dead jay, they come a'runnin', and those 'funerals' can last for up to half an hour.

But why? Western scrub jays live in breeding pairs and are not particularly social birds. “They’re really territorial and not at all friendly with other scrub-jays,”  said Teresa Iglesias, a U.C. Davis graduate student and co-author of a new study in Animal BehaviourIt turns out that death seems to signify danger, which opens up an even odder set of questions.

Working in the backyards of homes in Davis, Calif., Iglesias set up feeding tables to encourage visits from the jays. Then she videotaped their behavior when she placed a dead jay on the ground. She compared these reactions with the birds’ behavior when confronted with a dead jay that had been stuffed and mounted on a perch, a stuffed horned owl, and wood painted to represent jay feathers.

 (a)  painted object; (b) dead jay; (c) stuffed, perched jay; (d) stuffed owl predator. Teresa Iglesias, UC Davis photos

On encountering a dead jay, prostrate on the ground, jays flew into a tree and began a series of loud, screeching calls that attracted other jays. The summoned birds perched on trees and fences around the body and joined in the calling. These cacophonous gatherings could last from a few seconds to as long as 30 minutes.

Jays formed similar cacophonous gatherings in response to a mounted owl, but ignored painted wood. When confronted with a mounted jay, the birds swooped in on it as if it were an intruder.

Jays typically gathered within seconds of the first bird calling. If they did not, the first jay would often fly higher into a tree, apparently to call more widely.

“It looked like they were actively trying to attract attention,” she said. So if the calls are about danger, why do they summon others, rather than warning them off? It may be that having more jays present might mean more eyes to locate a predator, or more numbers to drive it away, she speculates. There might also be a learning component to the gatherings, if they help teach young jays about dangers in the environment.

While reactions of animals to their dead are sometimes called funerals, that does not imply that there is an emotional or ritual element to the behavior, Iglesias said. We simply don’t know enough about the emotional life of animals to understand that. But Iglesias isn’t ruling it out. “I think there’s a huge possibility that there is much more to learn about the social and emotional lives of birds,” she said.

Co-authors of the paper are UC Davis scientists Gail Patricelli, a professor of evolution and ecology, and Richard McElreath, an associate professor of anthropology.

Their work was supported by a Gates Millennium Graduate Scholarship from the Bill&Melinda Gates Foundation and UC Davis funds to support graduate students.