| Silvicultural practices alter forests in ways that can affect birds. The nature and magnitude of these effects depend on the habitat preferences of the species in question. Forest dwelling birds that have narrow habitat preferences are particularly vulnerable to the effects of silvicultural practices, as they are less able to adapt to habitat changes. The Bicknell's Thrush ( Catharus bicknelli) is a habitat specialist that occupies dense regenerating stands of managed forests. There is concern about the impact that precommercial thinning, a silvicultural practice that reduces stem density, may have on this species. I focused my study on this species and four others: two relative habitat specialists, the Fox Sparrow (Passerella iliaca) and the Blackpoll Warbler (Dendroica striata); and two relative habitat generalists, the Swainson's Thrush (Catharus ustulatus) and the Winter Wren (Troglodytes troglodytes). The purpose of my study is to determine the forest stages that are occupied by the Bicknell's Thrush and these four species, to examine their habitat preferences, and to examine the impact of precommercial thinning on their abundance. (Abstract shortened by UMI.)... |
