Abstract
AbstractIndividual diet specialization is known to occur in populations of generalist predators, where specific individuals develop specialist feeding strategies. Diet specialization has been reported in many raptor species, and it may be an important driver of intraspecific population structure. Here, we quantify the diet of five breeding pairs of Peregrine Falcons Falco peregrinus from an offshore island determined from prey remains collected over four breeding seasons. Three prey species accounted for 69.8 % of total prey frequency, with Manx Shearwater Puffinus puffinus the primary prey accounting for 47.3 % by frequency and 40.8 % by biomass. Herring Gull Larus argentatus was the second most important prey species by frequency (13.8 %) and biomass (29.8 %) followed by Domestic Pigeon Columba livia (frequency = 8.7 %, biomass = 7.0 %). Predation frequency on specific prey groups varied substantially between breeding pairs and months. Two pairs specialized on Manx Shearwater, one pair specialized on Herring Gull and Manx Shearwater, with the remaining two pairs having a relatively generalist diet of Manx Shearwaters, Domestic Pigeon and small passerines. Predation on Manx Shearwaters increased throughout the breeding season with a peak in total diet frequency of 63.8 % in July, with a concurrent decrease in Herring Gull predation frequency. Higher percentage of Manx Shearwater in the diet was able to explain 87 % of the variation in a narrower dietary breadth for the Peregrine pairs. Our results suggest individual diet specialization may be important for understanding population density in insular raptor populations.
Publisher
Cold Spring Harbor Laboratory
Reference44 articles.
1. The ecological causes of individual specialisation
2. Bang, P. & Dahlstrom, P. 2011. Animal tracks and signs. OUP, Oxford.
3. The Ecology of Individuals: Incidence and Implications of Individual Specialization
4. The marine Peregrines of the Northwest Pacific coast;The Condor,1960
5. Manx Shearwater recovery on Lundy: Population and distribution change from 2001 to 2013;Journal of the Lundy Field Society,2014