In winter, Common Kestrels minimize energy expenditure. And they prefer to use a low-cost low-profit technique of perch-hunting. The perch sites′ existence is the precondition of perch-hunting. So we can predict that Kestrel would prefer a habitat with more perch sites and perch site should have an important role in Kestrel′s hunting technique use, habitat selection and habitat use in winter. In order to test this prediction, we manipulated two areas in grassland. We increased potential perch site in one area with bamboo poles and keep another as control. We observed and compared the Kestrel′s use and their behaviors in these two areas.
We found the following results. More Kestrels at the area increasing perch sites than control were recorded. The Kestrels stayed at more perch sites area significant longer than control area. And at the area with more perch sites, of 7724% of total hunting, Kestrels hunted with the technique of perch-hunting. At the control area, Kestrels hunted only with the technique of flight-hunting. There was a significant correlation between the technique used by Kestrels and the areas with or without perch site. In the area increasing perch sites Kestrels spent 51.8% of time perching and 12.1% in air, and they were 30.1% and 34.8% respectively in control area. There was no significant difference of hunting profit between areas.
Our results suggest that perch sites has an important role in the selection of hunting techniques and habitat selection of Kestrels in winter and the Kestrels appear to prefer the habitat with suitable perch sites in winter.