Central-place foraging in an urban landscape: body mass of Common voles (Microtus arvalis Pall.) caught by breeding Kestrels (Falco tinnunculus L.) is positively correlated with availability of hunting sites

Sammanfattning

In the reproduction period a male Kestrel (Falco tinnunculus) is a central-place forager, i.e. it transports food from hunting grounds to a central location the nest. A central-place forager is predicted to take larger or more prey when distance to a foraging site is longer. We studied kestrels breeding in a large Central European city (population 1.7 million), whose main prey are common voles (Microtus arvalis). Kestrel nests are located in the centre and the outskirts, although common voles are scarce in the former. The aim of our study was to analyse the body mass of common voles found in pellets under kestrel nests and relate it to the availability of common vole habitats within 1 km from the nests, controlled for vole frequency in the pellets. We assumed that the greater availability of common vole habitats, the shorter the distance to a foraging site. We found that the body mass of common voles found in pellets was significantly positively correlated with the availability of their habitats, but was not affected by their frequency in pellets. Our results may indicate that, contrary to the central-place foraging rule, and irrespectively of the amount of other prey taken, the kestrels hunted smaller voles when foraging grounds were further away. This might stem from decreased selectivity caused by competition, either in the native territory (due to the high density of kestrels in the centre) or in territories of outskirt kestrels, invaded by city centre kestrels. On the other hand, due to lack of data on the body size of common voles in our study area, the results may suggest that common voles were on average smaller in the centre than in the outskirts. Although the published data do not support the second explanation, more research is needed to verify this.

Nyckelord

prey size selection; competition; urban environment

Publicerad i

Polish Journal of Ecology
2010, Volym: 58, nummer: 2, sidor: 387-392

UKÄ forskningsämne

Ekologi


Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/89269