Nest-Site Selection in the Cape Sugarbird

Abstract

Cape sugarbirds, Promerops cafer, preferred certain protea bushes as nest-sites. These bushes were characterized by relatively large leaves and dense foliage. Nests were usually placed in the central parts of bushes. Nest-sites were shielded from the cold night sky, and were associated with relatively favorable air temperatures and protection from wind in a season of unfavorable weather. Data on microclimate of nest-sites, together with those on heat loss from an incubating sugarbird, were interpreted in relation to nest-site selection as adaptive behavior promoting breeding success through conservation of energy. Sugarbirds nesting relatively high off the ground and in dense vegetation were considered to be decreasing the risk of exposure to predators.