Prooikeuze van Bruine Kiekendieven Circus aeruginosus in Groningen in 1995

Several methods were used to investigate the prey choice of Marsh Harriers during the breeding season: collecting prey remains, prey items and pellets on nests, systematically checking plucking posts and observing adults carrying prey. Of 291 prey items collected, 62% came from analyses of pellets, another 30% from pluckings, 7% from prey items found on nests and only 1% from identification of prey carried by adults. Common vole and hare were most often found as prey, of which the latter is particularly important in terms of biomass (Table 1). Starlings were frequently taken, probably because several Marsh Harrier nests were located in the vicinity of Starling roosts. The long list of birds probably reflects the fact that 1995 was characterised by low vole numbers. Almost half of all age-identified prey items were juvenile (65 out of 133).