This video is called Yakushima Island Frogs – Secret Wilderness: Japan – BBC.
From the BBC:
20 June 2012 Last updated at 07:42
Japanese deer ‘eavesdrop’ on monkeys for food
By Ella Davies, Reporter, BBC Nature
Sika deer “eavesdrop” on monkey chatter in order to find food, say scientists.
But when scientists played macaque calls from hidden speakers, the deer gathered nearby, indicating that they associate the sounds with benefits.
The results were published in the journal Behavioural Processes.
Dr Hiroki Koda who led the study said it was a good example of “possible interspecies communication” and that the deer seemed to be eavesdropping as a “foraging strategy”.
Yakushima Island lies to the south of Kyushu, Japan, and is protected by its Unesco world heritage status.
Researchers first reported the deer “gleaning” fruit from beneath trees where monkeys were feeding in 2004.
Dr Koda from the Primate Research Institute at Kyoto University wanted to investigate how the deer were able to follow the monkeys to foraging sites.
After hiding speakers in the forest he played recordings of calls commonly made between the monkeys during feeding sessions.
In his experiments, Dr Koda found that groups of deer often gathered near speakers during the playbacks, but they rarely gathered during “silent” periods when no calls were played.
Dr Koda now aims to investigate whether the deer can differentiate between the various food calls made by the monkeys.
He explained that there were “many common food items” that both deer and macaques ate.
“But of course,” he said, “some food items are used only by macaques, or only by sika deer.
“When macaques make food-associated calls [for] “macaque fruits”, sika deer might not [respond].”
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Some moths have evolved to “tune in” to the echolocation calls of bats in order to avoid them