Drongos mimic alarm calls to get a free lunch

African birds called drongos mimic other birds' alarm calls so that they can steal food from meerkats, scientists have found.

When a meerkat hears the alarm call, it drops its food and runs for cover thinking there's a predator around, allowing the drongo to get a free lunch.

Fork tailed drongo (Dicrurus adsimilis)
This is the first time scientists have shown that birds use alarm calls specifically to deceive other species.

'Meerkats have learnt to recognise the alarm calls made by different bird species and flee for cover when they hear them,' says Tom Flower from the University of Cambridge and author of the study, which is published in Proceedings of the Royal Society B.

This latest study suggests that fork-tailed drongos (Dicrurus adsimilis) have exploited the meerkats, using both their own and mimicked alarm calls to scare meerkats when they see them with scorpions or geckos.

Flower was working on meerkats in the Kalahari in southern Africa, when he noticed drongos following them around. He noticed the birds making alarm calls when there were no predators nearby and thought they must be doing it on purpose.

'Drongos are following meerkats and pied-babblers around in the hope of catching their food,' says Flower.

He thought the birds might moderate the number of times they lied to avoid blowing their cover. But this doesn't seem to be the case. 'They just turn up and steal as much food as they can get away with,' Flower says.

The researchers think the birds use a repertoire of alarm calls to keep meerkats on their toes, and to stop the creatures getting suspicious.


'It's like the boy who cried wolf: if drongos use the same call each and every time, meerkats will learn to ignore them, so instead they use different calls,' says Flower.

'Meerkats have to sit up and take note, because they've got too much to lose if they ignore the calls. They could lose their lives,' he adds

Drongos act as sentries for other animals - when they make alarm calls, meerkats and birds called pied-babblers know to run for cover. But if they do it too often, they won't be believed. So, they have to change which alarm call they use to stop meerkats ignoring them.


While scientists know that birds use their own and other birds' alarm calls to alert others to danger, until now, they weren't sure if the calls were used to deceive.


To show that fork-tailed drongos use deceptive alarm calls to get a free lunch, Flower's research had to satisfy three conditions. He had to show that alarm calls are used only in a deceptive context rather than an aggressive context; that true alarm calls made by drongos and other species sound the same as false alarm calls; and that meerkats and pied-babblers run for cover in response to recordings of both false and true alarm calls.

Researchers have suggested a number of possible functions for mimicry, such as that being able to copy other birds might help attract a mate, or that it lets animals communicate with other species. But no-one has shown that having a wide repertoire of calls attracts more females.

Flower's research shows a clear function for vocal mimicry, when before scientists could only speculate. He thinks mimicry is likely to be a fairly simple mechanism, and that drongos work out which calls are most effective by trial and error.


He's now keen to go back to the Kalahari to see how drongos learn to vary their calls.


by Tamera Jones

http://planetearth.nerc.ac.uk/news/story.aspx?id=856

Drongos mimic alarm calls to get a free lunch

African birds called drongos mimic other birds' alarm calls so that they can steal food from meerkats, scientists have found.

When a meerkat hears the alarm call, it drops its food and runs for cover thinking there's a predator around, allowing the drongo to get a free lunch.

Fork tailed drongo (Dicrurus adsimilis)
This is the first time scientists have shown that birds use alarm calls specifically to deceive other species.

'Meerkats have learnt to recognise the alarm calls made by different bird species and flee for cover when they hear them,' says Tom Flower from the University of Cambridge and author of the study, which is published in Proceedings of the Royal Society B.

This latest study suggests that fork-tailed drongos (Dicrurus adsimilis) have exploited the meerkats, using both their own and mimicked alarm calls to scare meerkats when they see them with scorpions or geckos.

Flower was working on meerkats in the Kalahari in southern Africa, when he noticed drongos following them around. He noticed the birds making alarm calls when there were no predators nearby and thought they must be doing it on purpose.

'Drongos are following meerkats and pied-babblers around in the hope of catching their food,' says Flower.

He thought the birds might moderate the number of times they lied to avoid blowing their cover. But this doesn't seem to be the case. 'They just turn up and steal as much food as they can get away with,' Flower says.

The researchers think the birds use a repertoire of alarm calls to keep meerkats on their toes, and to stop the creatures getting suspicious.


'It's like the boy who cried wolf: if drongos use the same call each and every time, meerkats will learn to ignore them, so instead they use different calls,' says Flower.

'Meerkats have to sit up and take note, because they've got too much to lose if they ignore the calls. They could lose their lives,' he adds

Drongos act as sentries for other animals - when they make alarm calls, meerkats and birds called pied-babblers know to run for cover. But if they do it too often, they won't be believed. So, they have to change which alarm call they use to stop meerkats ignoring them.


While scientists know that birds use their own and other birds' alarm calls to alert others to danger, until now, they weren't sure if the calls were used to deceive.


To show that fork-tailed drongos use deceptive alarm calls to get a free lunch, Flower's research had to satisfy three conditions. He had to show that alarm calls are used only in a deceptive context rather than an aggressive context; that true alarm calls made by drongos and other species sound the same as false alarm calls; and that meerkats and pied-babblers run for cover in response to recordings of both false and true alarm calls.

Researchers have suggested a number of possible functions for mimicry, such as that being able to copy other birds might help attract a mate, or that it lets animals communicate with other species. But no-one has shown that having a wide repertoire of calls attracts more females.

Flower's research shows a clear function for vocal mimicry, when before scientists could only speculate. He thinks mimicry is likely to be a fairly simple mechanism, and that drongos work out which calls are most effective by trial and error.


He's now keen to go back to the Kalahari to see how drongos learn to vary their calls.


by Tamera Jones

http://planetearth.nerc.ac.uk/news/story.aspx?id=856

South American cat mimics the call of its prey

July 2010: In a fascinating example of vocal mimicry, researchers have documented a wild cat species imitating the call of its intended victim - a small squirrel-sized monkey known as a pied tamarin. This is the first recorded instance of a wild cat species in the Americas mimicking the calls of its prey.


The extraordinary behaviour was recorded by researchers from the Wildlife Conservation Society and Federal University of Amazonas in the Amazonian forests of the Reserva Florestal Adolpho Ducke in Brazil. The observations confirmed what until now had been only anecdotal reports of wild cat species - including jaguars and pumas - actually mimicking primates, agoutis and other species in order to draw them within striking range.


Psychological cunning as well as physical agility
‘Cats are known for their physical agility, but this vocal manipulation of prey species indicates a psychological cunning which merits further study,' said WCS researcher Fabio Rohe.

Researchers first recorded the incident in 2005 when a group of eight pied tamarins were feeding in a ficus tree. They then observed a margay emitting calls similar to those made by tamarin babies. This attracted the attention of a tamarin "sentinel", which climbed down from the tree to investigate the sounds coming from a tangle of vines called lianas.

While the sentinel monkey started vocalising to warn the rest of the group of the strange calls, the monkeys were clearly confounded by these familiar vocalisations, choosing to investigate rather than flee. Four other tamarins climbed down to assess the nature of the calls. At that moment, a margay emerged from the foliage walking down the trunk of a tree in a squirrel-like fashion, jumping down and then moving towards the monkeys. Realising the ruse, the sentinel screamed an alarm and sent the other tamarins fleeing.

While this specific instance of mimicry was unsuccessful, researchers were amazed at the ingenuity of the hunting strategy.

‘This observation further proves the reliability of information obtained from Amazonian inhabitants,' said Dr Avecita Chicchón, director of the WCS's Latin America programme. ‘This means that accounts of jaguars and pumas using the same vocal mimicry to attract prey-but not yet recorded by scientists-also deserve investigation.'

WCS is monitoring populations of the pied tamarin-listed as Endangered on the IUCN's Red List-and is seeking financial support to continue the study, which aims to protect this and other species from extinction. Next to Madagascar, the Amazon has the highest diversity of primates on Earth.

These behavioural insights also are indications of intact Amazon rainforest habitat. WCS works throughout the Amazon to evaluate the conservation importance of these rainforests, which have become increasingly threatened by development.

http://www.wildlifeextra.com/go/news/margay.html