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Title: Conflict and cooperation in a colonially-breeding bird under adverse conditions
Author: Ashbrook, Kate
ISNI:       0000 0004 2740 0856
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2010
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Colonial breeding in birds is widely considered to provide a net benefit to individuals, outweighing costs such as increased competition for resources and intra- specific aggression. 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. In this thesis I show in the highly colonial Common guillemot Uria aalge how, during unfavourable conditions, the magnitude of these costs and benefits is dependent on the social environment of the breeding area. Parents were able to increase their foraging effort by leaving their chick unattended at the colony, but this unexpectedly resulted in heightened aggression towards unattended chicks from conspecifics, sometimes resulting in the chick being killed. However, despite the magnitude of this cost showing negative density-dependence, it did not result in diminished positive density-dependence of overall breeding success, suggesting that colonial breeding is still beneficial during unfavourable environmental conditions. Parents were also able to utilise a combined strategy of foraging at sea augmented by kleptoparasitism, stealing prey from neighbours, to increase chick provisioning rate and survival during adverse conditions, with no apparent cost to hosts. In contrast, cooperative behaviours were still evident, and I suggest that alloparental care, where an individual cares for unrelated young, is maintained via a combination of short- term benefits for the alloparent (additional parental experience) and chick (increased chick survival during periods of high parental non-attendance) and long-term benefits for the alloparent (future reciprocation of alloparental care). Investment in preening partners and neighbours was found to be negatively related to chick fledging success, suggesting that some cooperative behaviour may be disadvantageous during adverse conditions, when individuals apparently benefit more from investing in activities that directly increase reproductive success.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available