Extent of use of wetlands and surrounding habitat by over-wintering raptors on the Kanto Plain

Abstract

It is known that raptors, top of the food chain, prefer a variety of habitats and that many species especially prefer wetland habitats. Research has shown that large scale wetlands are very important to raptors, however, it is not known whether or not smaller wetlands around urban areas are important to these raptors. The focus of this study was to research the extent that over-wintering raptors use of wetlands surrounded by a relatively small natural habitat on the Kanto Plain and the importance of these habitats in urban areas. There were 5 research sites located on the Kanto Plain. Each site was studied for 20 hours (8:00am 4:00pm) from October to March in 2014 and 2015. QGIS and MAXENT models were used to analyze the raptors movements and the type of environment. The MAXENT model results showed that the accessibility of the wetlands and grassy areas had a big effect on the raptors use of these habitats. An increase in the raptors use of these habitats is thought to be due to the easy access of prey into these areas which in turn increased the raptors food supply. Due to the easy access there has been an increase of Osprey feeding on fish in the wetlands and especially an increase in Common Buzzard and Black Kite feeding on mice and small birds in the grasslands. In conclusion, it was found that easily accessible wetlands and grasslands had a good effect on the use of over-wintering raptors.