In Japan, Common kestrel nests in the limited sites such as ledge of cliffs and buildings and mainly forages voles in grasslands and farmlands. Also, Common kestrel has high cost of flight. Nakano city in Nagano prefecture is characterized by fruit cultivation, but the rice fields where Kestrels is suitable foraging area also exists. Which do Kestrels choose suitable foraging areas far from the nest or nearby other foraging areas? Does core area include nesting sites and foraging site? From the spring to summer, the nesting sites and foraging area of Kestrels in Nakano City were investigated using radio-tracking. We recorded the locations of the habitat use and foraging based on information from radio-tracking onto a 1 : 3000 map. In 2019, the home range sizes of 3 adult males (A-C) were calculated using the minimum convex polygon, the 95% kernel method, and the 50% kernel method as core areas. The male A had one small core area with a nesting site and a suitable foraging area, rice fields. The male B had two core areas, the northern one and southern one. Roost after reproductive failure and fruits gardens with lower foraging value were included in the northern one. Rice fields that are suitable foraging area was included in the southern one. The male C had large two core areas, eastern one and western one. The eastern one included a nesting site, and fruits gardens of lower foraging value, and the western one had good foraging rice fields. It is not necessary to divide the core area when the nesting site is close to the suitable foraging area, but the core area should be divided when the suitable foraging area is far away. It was suggested that Kestrels use suitable foraging areas at a distance, but tend to avoid short foraging areas with lower quality. Our results should lead to the understanding of basic ecology and environmental conservation of Common kestrel in Japan.
長野県中野市のチョウゲンボウによる営巣地と餌場の分割利用
