Wintering raptors in Kvismaredalen 1954/55—1989/90
Keywords:population studies, winter ecology, survey, monitoring, predator-prey interaction
The purpose of this study is to analyze whether any changes have occurred in the number of birds of prey wintering in Kvismaredalen in the middle of Sweden during the period 1954/55—1989/90. The results show that Golden Eagle Aquila chrysaetos, Rough-legged Buzzard Buteo lagopus, Sparrowhawk Accipiter nisus and Goshawk Accipiter gentilis were the most common species in the beginning of the monitoring period. At the end of the period Golden Eagle, White-tailed Eagle Haliaetus albicilla, Sparrowhawk and Goshawk together with Merlin Falco columbarius were the most numerous species. The study also shows that especially White-tailed Eagle and Merlin have increased their winter occurrence. The increase in White-tailed Eagles has taken place in the latter half of the 1980's whereas the Merlin has been relatively numerous during the whole of the 1970's and 1980's. Golden Eagle, and to a lesser extent also Sparrowhawk and Goshawk, have shown increases but these took place in the 1960's. Two species specializing in rodents, Rough-legged Buzzard and Short-eared Owl Asio flammeus, have both shown strong decreases. Buzzards Buteo buteo are also showing a decrease after a temporary increase during the 1960's. The fact that Kestrels Falco tinnunculus have not wintered since 1980/81 indicates a decrease for that species.
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