| Abstract: | There are few detailed analyses of the building materials used in bird nests. This study was part of a project on interrelations between northern Patagonian plants and birds. Nests of two hummingbird species distributed in the Andean portion of southern South America: the Green‐backed Firecrown Sephanoides sephaniodes and the White‐sided Hillstar Oreotrochilus leucopleurus, were collected along a precipitation gradient in northwestern Patagonia (Argentina). Nest morphology, structure, and composition (mostly botanical in origin) were analysed. Plants used as building materials are presented for each nest, arranged by location. The main structural materials were mosses (especially those with falcate leaves) entangled with spider web. Nests were concealed in their environments by the presence of mimetic material on the outer layer (spider cocoons, leprose lichens, feathers, and hairs). Soft material was the main component of the lining (pappi, feathers, spider web, and manufactured cotton). The variety of nesting materials decreased along the precipitation gradient, while the main structural components are generally fixed. |
