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BRANTA — Ryan A. Wilson-Parr

Hen Harrier Breeding Ecology: Prey diversity, the effects of weather and the implications for provisioning and yield

Institution: University of Glasgow, UK
Supervisors: RW Furness
Details: MRes 2005 (Completed)

Address: Flat 2/2 No.5 Nithsdale Road, Glasgow, G41 2AL (Apr 2006) Email

Subject Keywords: weather, prey susceptibility, foraging
Species Keywords: Hen Harrier Circus cyaneus



Although much research has explored how ecological conditions determine raptor foraging success and prey susceptibility/availability, relatively few studies have focused on the relationship between prey profitability and fluctuating climatic parameters. Closed circuit television footage of nesting Hen harriers Circus cyaneus was analysed in order to identify prey deliveries to nests, the proportions of which were then interpreted as being a viable reflection of prey species diversity and availability within their hunting range. This information was then coupled with weather records to show how local climatical conditions influence foraging behaviour and success. 134 hours and 108 hours of recorded footage from 2003 and 2004 respectively provided information on a total of 626 prey items. Of the identified prey items delivered to the nests, Meadow Pipits Anthus pratensis accounted for 74.6% and 81.7% of the prey species in 2003 and 2004 respectively. The results conform with the hypothesis that raptor generalists forage optimally when certain prey species are profitable. In 2003, there were no significant relationships between prey species and weather variables. In 2004, there was a significant relationship (p = 0.041) between passerines and microtines when tested against wind speed. The results partially support the hypothesis that variations in weather variables influence the susceptibility of certain prey species to raptor predation.

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