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Black-Headed Gulls and the Art of Begging

To: Birding Aus <>
Subject: Black-Headed Gulls and the Art of Begging
From: knightl <>
Date: Wed, 26 Nov 2003 17:15:44 +1000
http://www.nature.com/nsu/031124/031124-3.html

Chicks unite to increase parent-pestering
Coordinated begging extracts more food.
26 November 2003

JOHN WHITFIELD

Children accompanying their parents on Christmas shopping trips: take a tip from black-headed gull chicks, and team up with your siblings to increase pester power.

Gull nestlings put aside their differences and coordinate their begging to extract the maximum amount of regurgitated food from mum and dad, French researchers have discovered.

It flies in the face of conventional wisdom - children should fight each other for the biggest share of parental care. "Competition should increase with the number of chicks, but that's not what we found," says Nicolas Mathevon of Jean Monnet University in Saint-Etienne.

But offspring are also at odds with their parents, who might want to hold back their generosity for the benefit of future broods. This is the first time that a brood has been found to coordinate their efforts in the struggle for a meal, says Mathevon.

Watching gull nests from a floating platform nearby, Mathevon and colleague Isabelle Charrier saw begging decrease as the number of chicks rose from one to three 1.

Chicks in more crowded nests begged less, saving their energy. Begging became more coordinated and solo begging bouts declined as the nest filled.

The tactic exploits an adult black-headed gull's habit of ignoring who the beggar is and simply reacting to the overall amount of begging coming from the nest, the researchers conclude. Instead of rewarding loudest chick, the parents regurgitate food onto the ground - at which point, presumably, the chicks' solidarity breaks down and a free-for-all ensues.

In other species, such as warblers, the parents dish out food individually, so each chick must battle its siblings for the maximum share.

References
Mathevon, N. & Charrier, I. Parent-offspring conflict and sibling coordination in gulls. Proceedings of the Royal Society B , (Suppl.), doi:10.1098/rsbl.2003.0117 (2003).

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