Neighbours from hell: infanticide rife in guillemot colony - 17th September 2008
One of Britain's best-known species of seabird is increasingly attacking and killing unattended chicks from neighbouring nests due to food shortages.
Researchers from the University of Leeds and the Centre for Ecology & Hydrology observed a dramatic increase in the number of adult guillemots deliberately attacking chicks of the same species in the 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, published online in the Royal Society's journal Biology Letters, 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 leave their chick unattended and spend more time feeding, or should one of them remain to protect the chick from attacks from neighbouring birds even if it gets less food?
“The attacks were brutal and usually involved more than one adult as chicks fled from the initial attacking neighbour” said lead author Kate Ashbrook, of Leeds’ Faculty of Biological Sciences. “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 thirty years, and in that time chick attacks have been very rare occurrences.”
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 rarely leave them unattended, taking it in turns to find food. 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 almost half of all chicks unattended at some point during the day.
Surrounded by neighbours and open to the elements, guillemot colonies are a risky place to raise a chick. Although aggression between adults is common - breeding pairs often are in physical contact and ledges can be densely packed with up to thirty breeding pairs in one square metre – aggression toward chicks is unusual.
The research focused on a large established colony of guillemots that inhabit the Isle of May in Scotland. Co-author Professor Sarah Wanless from the Centre for Ecology & Hydrology has been monitoring this colony since 1981. She commented: “This research highlights how fragile the social fabric of a seabird colony is. Having a stressed, hungry neighbour isn’t good news if you’re an unattended guillemot chick.”
The research was funded by the Natural Environment Research Council.
Media coverage
Infanticide rife in guillemot colony - Telegraph online - 17 September 2008
Starving guillemots push rival chicks off cliffs - Guardian - 17 September 2008
Feathers fly as hunger bites and guillemots turn chick killers - Scotsman - 17 September 2008
Seabird chicks 'killed over food' - BBC News - 17 September 2008 - includes audio clip
Additional information
Media enquiries about this work should be directed to the Centre for Ecology & Hydrology press office.
A press release about this work was issued by Leeds University.
The Isle of May is a National Nature Reserve owned by Scottish Natural Heritage (external site). CEH has carried out seabird monitoring on the Isle of May for several decades. More information can be found here.
The research paper, titled ‘Hitting the buffers: conspecific aggression undermines benefits of colonial breeding under adverse conditions’ is published in the journal Biology Letters. Lead author Kate Ashbrook carried out the work as part of a NERC-funded PhD supervised by the University of Leeds and the Centre for Ecology & Hydrology.
Common Guillemots make no nest, their single egg is incubated on bare rock. The chick leave the breeding site about 20 days after hatching accompanied by the male parent. Chicks cannot fly when they leave the nest but are capable of diving as soon as they hit the water. Guillemots can dive to depths of 30–60m and depths of up to 180m have been recorded. During the breeding season the diet of colonies in the North Sea area mainly consists of sandeels and sprats.
