Sentinel birds sing the ‘watchman’s song’

April 18th, 2008 - 12:38 pm ICT by admin  

London, April 18 (IANS) Like soldiers guarding their posts in hostile territory and keeping comrades informed by radio that all is well, birds too are just as conscious about discharging similar “responsibilities”, according to a study. Researchers from the University of Bristol have demonstrated that by warbling a distinctive “watchman’s song”, birds scanning for danger ensure their larger feathered family can focus on foraging, and so get more food.

“These exciting results point to a great example of true cooperation. The unselfish behaviour of the sentry is probably rewarded down the line by the improved survival of group mates, which leads to a larger group size,” said lead researcher Andy Radford.

The new work shows that the foragers respond to the watchman’s song alone, whether or not they see a sentinel sitting in a tree.

In response to playbacks of recordings of the call, the foraging individuals spent less time looking out for predators, looked up less often, spread out more widely, and spent more time out in the open.

This means that they have more time for foraging, are less likely to lose track of prey, have more foraging patches to choose from and are less likely to encounter patches that have already been depleted.

As a consequence of these changes in behaviour, foragers had greater foraging success.

The work to study the watchman’s song was carried out by observing a bird species called the pied babbler, which is found in southern Africa.

Pied babblers live in groups of, on average, six or seven individuals and operate a sentinel system while they forage for prey such as scorpions and small snakes found beneath the surface of the sand.

These findings have been published in the latest issue of the journal Current Biology as well as Cell.

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