Foraging Birds Keep Guard

April 21, 2008 by  
Filed under Features

Researchers have recently discovered that certain bird species make use of a sentry when searching for food. This remarkable finding gives us fascinating insight into the survival tactics used by certain bird species.

A team of researchers from Bristol University recently traveled all the way to South Africa to study a group of pied babblers in the Kalahari Desert. It was already known that pied babblers lived in close-knit family groups that make use of a sentinel system, so they were an obvious choice for researches who wanted to study the effect that this system had on the group. The results of the research were very interesting.

It would seem that the pied babblers post a sentry high up in the tree tops. This bird’s job is to look out for potential predators that may cause a threat to his feathered comrades as they search for food. Findings show that birds foraging for food under the guard of this watchman spread out and search a wider area for food, thus increasing their chances of finding something and making them better foragers. The bird on duty employed a distinctive and specialized song in order to let other birds know that no dangers had been spotted and they could continue feeding safely. Pied babblers feed by digging in the sand for small animals such as scorpions. However, they need to be wary of larger predators such as cobras and puff adders.

The team of researchers, led by Dr Andy Radford, also found that the birds did not fret about whether or not they could see the sentinel in the tree but instead that their actions were a response to the song alone. Recordings of the watchman’s song were played back to the birds whose reaction was the same as if a real bird were present: the birds automatically became calmer and spread out in their search for food.

Only a few bird groups actually use the look-out system when feeding, but it has definitely proven to be beneficial for those that do. Improved survival of the group leads to an increase in population, which in turn increases survival rates when a group comes under attack from predators. The bird on duty sings continually using a chirp-like call that is repeated between five and fifty times a minute. The research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and has been published in Current Biology.

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