Opportunistic Use of a Wool-like Artificial Material as Lining of Tit (Paridae) Nests

Abstract

Abstract. The lining material is a key element of bird nests, serving primarily as insulation for the adult, eggs, and/or chicks, but collection of such material has an energetic cost. Our study investigated the nest-building effort of four species of tit (Paridae) in an English wood by quantifying the use of colored wool-like artificial material in nest lining from 2000 to 2010. We recorded the distances that birds carried the material from source to nest for each nest as an indirect measure of the energetic cost of collecting nest material to individual birds. Birds did not always use nest material from the nearest source to their nest, and some birds collected material from two, three or four well-separated sources. There was no detectable color preference in choice of material, and few birds traveled more than 200 m to gather the material. Use of the material appeared to depend on the species. Within defined areas around material dispensers not all individual Great Tits (Parus major) used the artifici...