Roosting, range use and foraging behaviour of the Sickle-billed Vanga, Falculea palliata, in Madagascar

Abstract

Roosting behaviour, range use and foraging behaviour of non-breeding Sickle-billed Vangas, Falculea polliata, a Malagasy endemic, were studied in the Ankarafantsika Strict Nature Reserve, northwestern Madagascar, in 1996 and 1997. Non-breeding birds farmed a flock and ranged daily between communal roosts and foraging areas. Roost sites were tall eucalypt trees (20–30 m) situated outside the forests, and the same trees were used repeatedly. Roosting flock size decreased during the breeding season, from October to December, due to the departure of breeding individuals. Mean sizes of daily home range and of foraging area were 68.6 ha (45–100 ha) and 14.1 ha (6–25 ha), respectively; much larger than those of breeding birds (3 ha). Sickle-billed Vangas foraged by probing their long and slender curved bills into holes and cracks in tree trunks or large branches. Dead trees or dead sections of live trees were preferred. The high abundance of large trees or dead trees in the deciduous forests allowed the flock to forage exclusively in this habitat. We suggest that communal roosts are located outside forests to avoid disturbance or predation by mammals. A foraging flock of Sickle-billed Vangas makes a round trip daily between the safe roosting sites and good foraging areas.