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September 21, 2012

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Scrub jays found to react to their dead

Sept. 13, 2012
Courtesy of UC Davis
and World Science staff

West­ern scrub jays sum­mon oth­ers to screech over the body of a dead jay, ac­cord­ing to new re­search from the Uni­vers­ity of Cal­i­for­nia, Da­vis. 

The ca­coph­o­nous bird “fu­ner­als” can re­portedly last for up to half an hour, though their pur­pose is un­known.

Westernscrub jays sum­mon oth­ers to screech over the body of a dead jay, ac­cord­ing to new re­search from the Uni­ver­si­ty of Cal­i­for­nia, Da­vis. A vid­e­o of the be­hav­ior is avail­a­ble on YouTube. (Cour­te­sy Te­re­sa Igle­si­as/UC Da­vis )

An­ec­do­tal re­ports have sug­gested that oth­er an­i­mals, in­clud­ing ele­phants, chim­panzees and birds in the crow fam­i­ly, re­act to dead of their spe­cies, said Te­re­sa Igle­sias, a grad­u­ate stu­dent at the uni­vers­ity who car­ried out the work. But few ex­pe­ri­men­tal stud­ies have ex­plored this be­hav­ior.

The new re­search by Igle­sias and her col­leagues ap­pears in the Aug. 27 is­sue of the jour­nal An­i­mal Be­hav­iour.

Na­tive to North Amer­ica, West­ern scrub jays live in breed­ing pairs and aren’t par­tic­u­larly so­cial. “They’re really ter­ri­to­rial and not at all friendly with oth­er scrub-jays,” Igle­sias said.

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.

Clock­wise from top left: A paint­ed ob­ject; a dead jay; a stuffed, perched jay; and a stuffed owl pred­a­tor are used to test jays' re­ac­tions to dif­fer­ent ob­jects. (Cour­te­sy Te­re­sa Igle­sias, UC Da­vis )

On en­coun­ter­ing a dead jay ly­ing on the ground, jays flew in­to a tree and be­gan a se­ries of loud, screech­ing calls that at­tracted oth­er jays, Igle­sias said. The sum­moned birds perched on trees and fences around the body and joined in the call­ing, ac­cord­ing to the re­port. 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, Igle­sias said. If they did­n’t, 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.

The pur­pose of the calls seems to be to alert oth­er birds of dan­ger, Igle­sias said. But why the calls sum­mon oth­ers, rath­er than warn­ing them off, is un­clear. 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, Igle­sias said.

While re­actions of an­i­mals to their dead are some­times called “fu­ner­als,” that doesn’t imply there is an emo­tion­al or rit­u­al el­e­ment to the be­hav­ior, Igle­sias said; we don’t know enough about an­i­mals’ emo­tion­al lives 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.

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Western scrub jays summon others to screech over the body of a dead jay, according to new research from the University of California, Davis. The cacophonous bird “funerals” can reportedly last for up to half an hour. Anecdotal reports have suggested that other animals, including elephants, chimpanzees and birds in the crow family, react to dead of their species, said Teresa Iglesias, a graduate student at the university who carried out the work. But few experimental studies have explored this behavior. The new research by Iglesias and her colleagues appears in the Aug. 27 issue of the journal Animal Behaviour. Western scrub jays live in breeding pairs and aren’t particularly social. “They’re really territorial and not at all friendly with other scrub-jays,” Iglesias said. 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. On encountering a dead jay lying on the ground, jays flew into a tree and began a series of loud, screeching calls that attracted other jays, Iglesias said. The summoned birds perched on trees and fences around the body and joined in the calling, according to the report. 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, Iglesias said. If they didn’t, 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. The purpose of the calls seems to be to alert other birds of danger, Iglesias said. But why the calls summon others, rather than warning them off, is unclear. 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, Iglesias said. 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.