Food shortage forces seabirds to prey on unattended fledglings

September 17th, 2008 - 3:54 pm ICT by IANS  

London, Sep 17 (IANS) One of Britain’s best-known seabird species is increasingly killing unattended chicks in neighbouring nests due to food shortages, a research has found.Leeds University and Centre for Ecology & Hydrology researchers observed a sharp increase in the number of adult guillemots deliberately attacking chicks of the same species last year.

Hundreds of such attacks occurred, and many were fatal, with chicks being pecked to death or flung from cliff ledges. These disturbing findings, indicate that social harmony - even in long-established colonies - can break down when conditions get tough, for example if starvation looms.

The study highlights a previously unsuspected parental dilemma: should both parents leave their chick unattended and spend more time feeding, or should one of them stay back to protect the chick from attacks from neighbouring birds even if they get less food?

“The attacks were brutal and usually involved more than one adult as chicks fled from the initial attacking neighbour,” said co-author Kate Ashbrook, of Leeds.

“More than two thirds of all documented chick deaths in the sample area were caused by attacks from neighbouring parents. Yet this particular colony has been monitored for almost 30 years, and in that time chick attacks have been very rare occurrences,” She added.

Common guillemots (Uria aalge) are attentive parents and rear only one chick during the breeding season, which runs from April to July. Because chicks are vulnerable to attacks from predatory gulls, parents seldom leave them unattended, taking turns to find food, reports Eurekalert.

However, a decline in prey in recent years has led to both parents being forced to search for food at the same time. Researchers witnessed that almost half of all chicks were unattended at some point during the day.

These findings were published online on Wednesday in the Royal Society journal Biology Letters(1).

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