Effects of selective logging on forest bird populations in a fragmented landscape

We evaluated the effects of perforation, or the creation of small gaps, within a mature, deciduous forest in southern Illinois (U.S.A.) on abundances of breeding birds. Openings of 0.02-0.4 ha were created by group and single-tree selection logging within a 2000-ha tract of forest. We used point counts to compare abundances of birds in uncut forest with those in similar adjacent forest compartments that were recently cut (1-5 years previously) and less recently cut (10-15 years earlier). Most species of forest birds were not significantly less common in logged tracts. Only Red-eyed Vireos (Vireo olivaceus) and Ovenbirds (Seiurus aurocapillus) were significantly more numerous in uncut forest, but the vireo responded negatively to cuts at sites on ridges only, not in ravines, whereas Ovenbird populations differed substantially among years. Blue Jays (Cyanocitta cristata), important nest predators, were significantly more abundant in cut than uncut forest, but brood parasitic Brown-headed Cowbirds (Molothrus ater) showed no consistent differences. Populations of gap-dependent species such as Hooded Warbler (Wilsonia citrina), Indigo Bunting (Passerina cyanea), Whiteeyed Vireo (Vireo griseus), and Carolina Wren (Thryothorus ludovicianus) were dramatically larger in recently cut forest, with populations of most species reaching a peak 2-3 years after cutting. Between 5 and 10 years after cutting, nearly all gap-dependent species had returned to population levels comparable to those in uncut forest. Species dependent upon larger gaps, such as Yellow-breasted Chat (Icteria virens), Blue-winged Warbler (Vermivora pinus), and Prairie Warbler (Dendroica discolor), were absent. We conclude that the first cutting cycle in selective logging had only a minor effect on the forest bird community composition and created a short-lived availability of habitat for gap species. In the southern Illinois landscape, selective logging appeared to add little to the existing effects of forest fragmentation. Effects of perforation may differ in more continuously forested landscapes, however, and may be influenced by total basal area of timber removed and by the length of the inter-cut interval.