Abstract
Colonial breeding in birds is widely considered to benefit individuals through
enhanced protection against predators or transfer of information about foraging
sites. This view, however, is largely based on studies of seabirds carried out
under favourable conditions. Recent breeding failures at many seabird colonies
in the UK provide an opportunity to re-examine costs and benefits of coloniality
under adverse conditions. Common Guillemots Uria aalge are highly colonial
cliff-nesting seabirds with very flexible parental care. Although the single chick is
normally never left alone, more than 50% of offspring were left unattended at a
North Sea colony in 2007, apparently because poor conditions forced both
parents to forage simultaneously. Contrary to expectation, unattended chicks
were not killed by avian predators. Rather, although non-breeders and failed
breeders sometimes provided alloparental care, unattended chicks were
frequently attacked by breeding guillemots at neighbouring sites, often with
fatal consequences. These results highlight a previously unsuspected trade-off
between provisioning chicks and avoiding conspecific attacks, and indicate that
understanding how environmental conditions affect social dynamics is crucial
to interpreting costs and benefits of colonial breeding.
Keywords:
density dependence,
social dynamics,
chick neglect,
infanticide,
environmental change
http://dx.doi.org/10.1098/rsbl.2008.0417
Notes
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- Ashbrook K, Wanless S, Harris MP & Hamer KC (2008) "Hitting the buffers:
conspecific aggression undermines benefits of colonial breeding under adverse
conditions" Biol Lett 4(6):630-633
[notes]
http://dx.doi.org/10.1098/rsbl.2008.0417
- Ashbrook et al (2008)
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