Blackburnian Warbler Setophaga fusca Scientific name definitions

The Blackburnian Warbler is a brilliantly colored Nearctic-Neotropical migrant and one of a group of Setophaga wood warblers that coexist during the breeding season in the northeastern coniferous forests of North America. Birds of this group are so similar structurally that early students of bird foraging and niche partitioning wondered how they coexisted. They are now known to separate ecologically by foraging areas (Macarthur 1958 Macarthur, R. H. (1958). Population ecology of some warblers of northeastern coniferous forest. Ecology 39:599-619. Close , Morse 1968a Morse, D. H. (1968a). A quantitative study of foraging of male and female spruce-woods warblers (Parulidae). Living Bird 3:9-43. Close ), the Blackburnian Warbler exploiting a treetop niche.

Although the Blackburnian Warbler is morphologically similar to many of its congeners that share these forests, it differs strikingly from them in coloration. Breeding males are characterized by blazing orange plumage over much of the anterior part of their body, a color not shared by other Setophaga species.

In common with some other Setophaga wood warblers, the range of the Blackburnian Warbler extends both to the northwest in Canada and to the southeast along the Appalachian Mountains. In the southern part of its breeding range, this species specializes on hemlock (Tsuga canadensis), although like the Black-throated Green Warbler (Setophaga virens) it sometimes inhabits deciduous forests as well. Throughout its breeding grounds, this insectivorous species appears to feed primarily on lepidopteran larvae, which it gleans from small branches high in trees. It nearly always builds its nest in conifers, on small limbs well out from the trunk.

Populations of this species are vulnerable owing to the loss of preferred winter forest habitat in northern South America, although Breeding Bird Survey data suggest that their numbers have been stable to moderately increasing in recent decades. The Blackburnian Warbler is a forest-interior species and numbers decline in forest fragments. Southerly populations breeding in eastern hemlock and Fraser fir are at risk as a result of wooly adelgids responsible for heavy mortality of these trees.

Some aspects of the Blackburnian Warbler's breeding biology are relatively well known, including foraging (Macarthur 1958 Macarthur, R. H. (1958). Population ecology of some warblers of northeastern coniferous forest. Ecology 39:599-619. Close , Morse 1968a Morse, D. H. (1968a). A quantitative study of foraging of male and female spruce-woods warblers (Parulidae). Living Bird 3:9-43. Close ), population dynamics (Morse 1976b Morse, D. H. (1976b). Variables affecting the density and territory size of breeding spruce-woods warblers. Ecology 57:290-301. Close ), interspecific interactions (Morse 1976a Morse, D. H. (1976a). Hostile encounters among spruce-woods warblers (Dendroica Parulidae). Animal Behaviour 24:764-771. Close ), habitat selection (Morse 1976b Morse, D. H. (1976b). Variables affecting the density and territory size of breeding spruce-woods warblers. Ecology 57:290-301. Close ), and singing behavior (Morse 1967c Morse, D. H. (1967c). The contexts of songs in the Black-throated Green and Blackburnian warblers. Wilson Bulletin 79:62-72. Close ). Some ecological studies have been performed on their wintering grounds in Colombia (Chipley 1980 Chipley, R. M. (1980). Nonbreeding ecology of the Blackburnian Warbler. In Migrant Birds in the Neotropics (A. Keast and E. S. Morton, Editors), Smithsonian Institution Press, Washington, DC, USA. pp. 309–317. Close , Lerner and Stauffer 1998 Lerner, S. de la Zerda and D. F. Stauffer. (1998). Habitat selection by blackburnian warblers wintering in Colombia. Journal of Field Ornithology 69:457-465. Close ). Recent studies have focused on the effect of silvicultural practices on this and other species (e. g., Hagen et al. 1996 Hagen, J. M., W. M. Vander Haegen and P. S. McKinley. (1996). The early development of forest fragmentation effects. Conservation Biology 10:188-202. Close , Meiklejohn and Hughes 1999 Meiklejohn, B. A. and J. W. Hughes. (1999). Bird communities in riparian buffer strips of industrial forests. American Midland Naturalist 141 (1):172-184. Close , Hobson and Bayne 2000b Hobson, K. A., and E. Bayne (2000). Effects of forest fragmentation by agriculture on avian communities in the southern boreal mixed woods of western Canada. Wilson Bulletin 112(3):373–387. Close , Cumming and Diamond 2002 Cumming, E. E. and A. W. Diamond. (2002). Songbird community composition versus forest rotation age in Saskatchewan boreal mixedwood forest. Canadian Field-Naturalist 116 (1):69-75. Close ). However, information on many aspects of the species' life cycle is rudimentary. Little is known of its migratory ecology. Many aspects of its breeding ecology remain largely or completely unknown, in part a consequence of its treetop existence in northern forests.