Ecology of gyrfalcons, Falco rusticolus, in the central Canadian Arctic: diet and feeding behaviour

摘要: Diet and aspects of feeding behaviour in a population gyrfalcons (Falco rusticolus) the Northwest Territories were examined between 1984 1986. Three prey species, rock ptarmigan (Lagopus mutus), arctic ground squirrel (Spermophilus parryii), hare (Lepus arcticus), composed 96.5% total biomass identified. Ptarmigan hares taken May June all years (98.2% biomass). Juvenile squirrels used extensively July August 1985 but not 1986, when production fell to almost zero; continued be dominant species throughout that summer. Because densities breeding remained relatively constant during study, those juvenile did not, it appeared responded functionally varying availability prey. Mean weight (250 g) by male was significantly less than (330 g) females. As predicted optimal foraging theory, ave...