Nest-Site Selection and Hatching Success at a Mixed-Species Colony of Black-Winged Stilts Himantopus Himantopus and Gull-Billed Tern Gelochelidon Nilotica

Abstract

Nest-site characteristics and hatching success were studied at a mixed-species colony of Black-winged Stilts Himantopus himantopus and Gull-billed Tern Gelochelidon nilotica in AghGol wetland, Hamedan Province, Iran during the 2008 breeding season. Species-specific preferences and a possible correlation between hatching success and nest location were analysed. Black-winged stilts select significantly closer points to the water edge than random points while the distance to the water edge did not vary between preferred and non-preferred locations for Gull-billed Terns. Plant density was significantly higher in Gull-billed Terns than Black-winged Stilt nest-sites, which also preferred areas of lower plant density. Hatched Gull-billed Tern nests had significantly higher plant density around the nest than failed nests. Overall, hatching success of Gull-billed Tern was higher than that of Black-winged Stilt; mainly because of disturbances resulting from a decrease in the water level.