Setophaga striata

Phylogenetic analyses of sequences of mitochondrial and nuclear DNA (Lovette et al. 2010) indicate that all species formerly placed in Dendroica, one species formerly placed in Wilsonia (citrina), and two species formerly placed in Parula (americana and pitiayumi) form a clade with the single species traditionally placed in Setophaga (ruticilla). The generic name Setophaga has priority for this clade (AOU 2011).

Banks and Browning (1995) rejected the name Dendroica breviunguis for this species, but others have used it in the past (Hunt and Eliason 1999). Burleigh and Peters (1948) described morphological variation in eastern and western birds and proposed subspecies Dendroica striata lurida (western) and D. s. striata (eastern); Parkes (1954) subsequently refuted this distinction, and subsequently no subspecies were recognized by the American Ornithologists' Union (AOU 1957).

Large breeding range in North America; numerous; secure.

Breeding range extens from western and north-central Alaska and northwestern Canada (Mackenzie Delta) to northern Labrador and Newfoundland, and south to southern Alaska, south-central British Columbia, northern Saskatchewan, eastern New York, northern New England, and Nova Scotia. During the northern winter, this warbler occurs primarily in the Amazon basin in Colombia, Venezuela, Ecuador, Peru, Brazil, and Bolivia, and has been found several times in southern South America, where the species is perhaps common locally in southeastern Brazil (Ridgely and Tudor 1989). This species is an autumn transient in Bermuda, Bahamas, eastern Greater Antilles, and throughout the Lesser Antilles; spring transient in western Greater Antilles and Bahamas; casual in Central America (Stiles and Skutch 1989).

This species isrepresented by a large number of occurrences (subpopulations).

Threats include habitat loss at breeding and nonbreeding areas, in-flight collisions during migration, mortality during migration associated with increased storm frequency/severity, and climate change related habitat loss of favored riparian and bog habitats.

Habitat loss: Breeding densities declined in 20-meter riparian buffers after the surrounding habitat was removed by clearcutting in the Canadian boreal forest (Darveau et al. 1995). Degradation of red spruce and subalpine spruce-fir forests from acid rain in the northeastern United States and southeastern Canada may adversely affect this species (Darveau et al. 1995, Hunt and Eliason 1999, Moegenburg and Greenberg 2004). Deforestation on wintering grounds in lowland Amazonia may also impact the species; blackpoll warblers were considered one of the 12 species most vulnerable to extinction due to tropical deforestation (Petit et al. 1993, Petit et al. 1995).

Collisions: This species commonly collides with towers during migration (e.g., communication, wind turbines, buildings), presumably due to their attraction to lights and disorientation during night migration (Bent 1953, Ogden 1996, Hunt and Eliason 1999). Hundreds to thousands of deaths have been reported at single locations over one season (Ogden 1996). In a study of tower kills in the United States since 1949, blackpoll warblers were the seventh most commonly killed bird (of 230 reported species) with 6,304 documented dead at 32 towers (Shire et al. 2000). Of concern is the marked increase in the number of towers constructed in the United States and Canada following the growth of the cell phone industry and wind energy development (Shire et al. 2000, ADFG 2005).

Climate change: Rates of survival and productivity of trans-oceanic migrants are associated with El Niño and North Atlantic Oscillation events (Nott et al. 2002). Abundance of breeding blackpoll warblers from 1967 to 1996 was negatively correlated with the frequency and severity of storms over the Atlantic Ocean and Gulf of Mexico during fall migration the previous year (Butler 2000). During this long, transoceanic flight (the longest of any North American warbler), birds may be particularly susceptible to mortality, which has been found to account for 90% of annual mortality in congeneric Black-throated Blue warbler Dendroica caerulescens (Sillett and Holmes 2002). Climate change may reduce riparian and bog habitats favored by this species through permafrost degradation and drying (ADFG 2005).