HOME RANGE, MOVEMENT, AND NESTING OF LEAST BITTERNS IN WESTERN NEW YORK

Abstract

We studied the nesting ecology of Least Bitterns (Ixobrychus exilis) during 1999 and 2000 within an 8,000-ha wetland complex in western New York. We used radio telemetry to track 33 adult Least Bitterns to locate nests and determine movement patterns, and 12 chicks to determine postfledging movements. Least Bittern Mayfield nest success rates were 43.8% (n = 38) in 1999 and 52.5% (n = 35) in 2000, and they renested and had double broods. Mean home range of adults was 9.7 ha (n = 33), but varied (range = 1.8–35.7 ha) depending upon whether birds used one or two areas during the breeding season. The mean movement of chicks from their nests was 13.4 m between capture and 23 days posthatching (n = 11), and 29.4 m when 24–27 days old (n = 4). Mean age at first flight was about 29 days old (n = 4). Vegetational structure and composition and marsh size appear to be important factors to consider when managing for Least Bittern populations.