Researchers find scrub jays congregate over dead

Sep 03, 2012 by Bob Yirka report
Aphelocoma californica. A juvenile Western Scrub Jay in Santa Cruz, California, USA. Image credit: Tyler Karaszewski/Wikipedia.

(Phys.org)—A small group of researchers from the University of California, Davis has found that a species of bird, the western scrub jay, responds to the presence of a dead specimen of one of their own, by calling out loudly to others of their kind and congregating around the body for up to day or two. The team, made up of T.L. Iglesias, R. McElreath and G.L. Patricelli discovered the birds' unique behavior by leaving dead jays in areas where the birds are known to exist and, as they describe in their paper published in the journal Animal Behavior, watching as they called out to others to join in, forming a loud aggregation.

In addition to leaving dead jays in observable places, e.g. back yards, the team also deposited stuffed jays and owls, as well as pieces of dead wood. The idea was to compare their reactions to different objects. They found that upon discovering the dead carcass of one of their own, the birds would fly down to be near it and call out to others who would eventually join them. The calls were apparently loud enough for other birds, away, to hear and join in, creating what the team describes as a great "cacophonous ."

The team noted that the birds also reacted to the stuffed , calling out and aggregating around them but in a completely different way. When they spied the stuffed , a known predator, they called out in obvious alarm, alerting others to its presence. They did so when discovering the stuffed jays as well, but rather than behaving as if alarmed, they tried to drive it away, a normal behavior when encountering other birds that appear to be invading its territory, clearly believing it to be alive due to its upright stance.

Interestingly, the team also found that when the birds congregated around their lost compatriot, they ceased foraging, sometimes for as long as forty eight hours. The research group doesn't believe the congregating is a form of mourning, but is instead a way for the birds to convey to all of the others in the area, that some unidentifiable threat is about and that they all need to be on special heightened alert, at least for awhile.

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More information: Western scrub-jay funerals: cacophonous aggregations in response to dead conspecifics, Animal Behaviour, dx.doi.org/10.1016/j.anbehav.2012.08.007

Abstract
All organisms must contend with the risk of injury or death; many animals reduce this danger by assessing environmental cues to avoid areas of elevated risk. However, little is known about how organisms respond to one of the most salient visual cues of risk: a dead conspecific. Here we show that the sight of a dead conspecific is sufficient to induce alarm calling and subsequent risk-reducing behavioural modification in western scrub-jays, Aphelocoma californica, and is similar to the response to a predator (a great horned owl, Bubo virginianus, model). Discovery of a dead conspecific elicits vocalizations that are effective at attracting conspecifics, which then also vocalize, thereby resulting in a cacophonous aggregation. Presentations of prostrate dead conspecifics and predator mounts elicited aggregations and hundreds of long-range communication vocalizations, while novel objects did not. In contrast to presentations of prostrate dead conspecifics, presentations of a jay skin mounted in an upright, life-like pose elicited aggressive responses, suggesting the mounted scrub-jay was perceived to be alive and the prostrate jay was not. There was a decrease of foraging in the area during presentations of prostrate dead conspecifics and predator mounts, which was still detectable 24 h later. Foraging returned to baseline levels 48 h after presentations. Novel objects and mounted jays did not affect foraging. Our results show that without witnessing the struggle and manner of death, the sight of a dead conspecific is used as public information and that this information is actively shared with conspecifics and used to reduce exposure to risk.

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User comments : 5

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Sancho
1 / 5 (3) Sep 03, 2012
Anthropomorphism, so called, in the service of Science is no crime, even if scientists would prefer not to be reminded that human nature is, in fact, rooted in Nature. Is one really to believe the researcher's theory that the birds congregate for days, without eating, in a place of danger?
Torbjorn_Larsson_OM
5 / 5 (4) Sep 03, 2012
One is to accept, not believe, the putative observation and the hypothesis until either has been independently rejected. It is after all a peer reviewed result.

It is a nice observation and hypothesis as well, since it may predict one of the reasons we ourselves started with a similar behavior - to reduce risk. It is actually the reverse of anthropomorphism, since it may predict human behavior in terms of other animal behavior.
JS7
4.7 / 5 (3) Sep 03, 2012
"The research group doesn't believe the congregating is a form of mourning"
And yet they offer no basis for this dubious conclusion. The persistent denial of anything natural in animals is one of the most embarrassing and useless tendencies in modern science.
defactoseven
4.7 / 5 (3) Sep 03, 2012
"The research group doesn't believe the congregating is a form of mourning, but is instead a way for the birds to convey to all of the others in the area, that some unidentifiable threat is about and that they all need to be on special heightened alert, at least for awhile."

I am not going to pretend I know enough about the subject to make any realistic assessment of the quoted statement above, BUT I just can't figure out how they could come to this conclusion. You would have to be a bird mind reader to say the birds convey "some unidentifiable threat" which is bazaar to say the least. Heightened alert? Not eating for possibly 48 hours? How does that make sense in a natural world?

Someone help me understand how to know the mind of a bird.
Torbjorn_Larsson_OM
not rated yet Sep 04, 2012
JS7, defacto7, the work seems to present a minimal hypothesis about the background inducing the behavior, it is an "Animal Behavior" article after all. They may or may not be able to test that hypothesis, I haven't checked. In the terms of defactoseven, they are abstaining from 'knowing the mind of the bird' and looking for evolutionary advantages. And it is impossible from the wording to tease out if it is the article's description of what the groups work amounts to, or if the researchers themselves state this in the paper or when interviewed about the work.

Mourning in animals such as us can then be a way of strengthening such existing behaviors.

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