Orangutans use calls for a variety of reasons
Jeremy Hancemongabay.com
March 10, 2010
"Orangutans have a rich repertoire of calls, however only sexually mature, flanged males emit long-distance calls with a series of long booming pulses and grumbles," explains co-author Dr Brigitte Spillmann. "Individual recognition is important in long distance communication when individuals are separated beyond visual contact, we examined whether individual identity and context were also encoded into a long call."
 Orangutan in Borneo. Photo by: Rhett A. Butler. |
By observing female orangutans' response to the male's long-calss, the team found that females could distinguish not only which male was calling but also the context of the call—whether it was spontaneous or in response to other calls or downing trees.
Females with offspring would move away when they heard spontaneous calls while available females appeared interested and moved closer, clearly indicating that the spontaneous calls were made largely to attract females.
However, both sets of females—those with offspring and those sexually-active—ignored long calls that were in response to other calls or 'snag crashing', since the calls were not directed at the females.
The Bornean orangutan (Pongo pygmaeus) is classifed as Endangered by the IUCN Red List, while the Sumatran orangutan (Pongo abelii) is considered Critically Endangered. Both species are threatened by habitat loss for plantations and logging.
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