How do birds react when a member of their flock dies? Apparently, for western scrub jays, commotion ensues.

These birds call loudly when they come upon another jay that is dead, attracting nearby birds, which often join in the noise. A team of scientists from UC Davis hypothesized that these “cacophonous aggregations” may function to warn other birds of potential danger. To test this hypothesis, the scientists tracked the response of the birds to a dead jay laying on the ground, and compared those with the birds’ reactions to three other stimuli: a stuffed and mounted jay, a stuffed and mounted great horned owl, and a neutral object that was somewhat similar in shape and color to a dead bird (painted pieces of wood).

The researchers found that the jays didn’t respond at all the painted wood, and the stuffed jay only elicited loud gatherings about a third of the time. The stuffed predatory owl, however, elicited cacophonous aggregations more than 80 percent of the time, almost exactly as often as the dead jay did. Not only did the dead jay and the stuffed owl incite the same type of behavior with similar frequency, but both of them decreased the amount of time that the jays spent foraging.

Together, these results strongly suggest that jays interpret the dead birds as a sign of risk, and that they call to alert other birds to the possibility of danger. Although attracting attention in a dangerous situation may seem counterintuitive, the researchers suggest that the calls may help gather a mob that would deter a predator, or may serve to warn mates and offspring in a nest.

In the paper’s title, the authors refer to these loud gatherings as “funerals,” a term that, to some people, suggests that there is an emotional component to this phenomenon. The use of the word “funeral” has been criticized as unnecessarily anthropomorphic and somewhat misleading, as the study didn’t address any questions regarding animal emotion. However, despite the questionable title, the study greatly improves our understanding of cognition, communication, and risk-taking behavior in jays.

Animal Behaviour, 2012. DOI: 10.1016/j.anbehav.2012.08.007 (About DOIs).