THE RELATIVE IMPORTANCE OF NESTING AND FORAGING SITES IN SELECTION OFBREEDING TERRITORIES BY TOWNSEND WARBLERS

Citation
Sm. Matsuoka et al., THE RELATIVE IMPORTANCE OF NESTING AND FORAGING SITES IN SELECTION OFBREEDING TERRITORIES BY TOWNSEND WARBLERS, The Auk, 114(4), 1997, pp. 657-667
Citations number
73
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Ornithology
Journal title
ISSN journal
0004-8038
Volume
114
Issue
4
Year of publication
1997
Pages
657 - 667
Database
ISI
SICI code
0004-8038(1997)114:4<657:TRIONA>2.0.ZU;2-M
Abstract
We investigated habitat selection by the Townsend's Warbler (Dendroica townsendi), a Neotropical-Nearctic migrant that breeds primarily in m ature coniferous forests. From 1993 to 1994, we compared the features of habitat selected for nest sites and foraging sites with those selec ted for territories in mature, mixed coniferous-deciduous forests in s outh-central Alaska. We also tested the prediction that large conifers are selected for nesting and foraging sites. Females placed nests in relatively large white spruce (Picea glauca) and consistently chose ne st trees that were within areas of higher densities of large white spr uce than were generally available. Nesting areas also had a higher den sity of small white spruce than was generally available, which may hav e been important in concealing nests from predators. Vegetation featur es selected for foraging differed from those selected for nesting and varied seasonally. Foraging was concentrated in medium-sized white spr uce during the prehatching stage and became more generalized across co niferous and deciduous vegetation during the posthatching stage. Adult s foraged in large white spruce in direct proportion to their availabi lity on the study areas. Territories, which encompassed both nesting a nd foraging areas, were heterogeneous in vegetation structure and flor istics. Areas selected for territories clearly reflected availability of the large white spruce selected for nest sites but did not reflect selection of medium white spruce for foraging. Characteristics of habi tats varied with specific resource needs, but the distribution of Town send's Warblers was most strongly related to specific habitat requirem ents for nest sites.