Black-throated Blue Warbler Setophaga caerulescens Scientific name definitions

A denizen of the forest interior, the Black-throated Blue Warbler inhabits large tracts of relatively undisturbed hardwood and mixed deciduous-coniferous forests in the northeastern United States and southern Canada, and south at higher elevations of the Appalachian Mountains to northern Georgia. Most individuals migrate along the eastern seaboard from the Appalachians to the Atlantic coast, and overwinter in forested habitats of the Greater Antilles from Puerto Rico to Cuba, Jamaica, and Hispaniola, with some in the Bahamas, along the coast of the Yucatan and Belize, and a few in south Florida.

Males and females of this species differ strikingly in appearance, and were even considered separate species by early naturalists, including Alexander Wilson (Wilson 1810 Wilson, A. (1810). American Ornithology or the Natural History of Birds of the United States. Volume 2. Bradford and Inskeep, Philadelphia, PA, USA. Close ) and John James Audubon (Audubon 1841 Audubon, J. J. (1841). The Birds of America. Volume 3. J. J. Audubon, Philadelphia, PA, USA. Close ). Males are unmistakable in their blue, black, and white plumage, while females are a more cryptic greenish-gray in color. This is one of the parulid warblers that does not molt into a “confusing fall plumage,” so individuals can be identified easily year-round. Populations differ somewhat in plumage, notably in the amount of dark streaking on the crown, dorsal feathers, and the size of white patches in wings—characters once used to separate the two subspecies.

Being a bird of forested landscapes, the Black-throated Blue Warbler likely experienced population declines when eastern North America was deforested and settled by Europeans in the 18^th and 19^th centuries (Whitney 1994 Whitney, G. G. (1994). From coastal wilderness to fruited plain: a history of environmental change in temperate North America from 1500 to the present. New York: Cambridge Univ. Press. Close ). As fields and pastures in the heart of its range returned to forest mostly in the 20^th century, its populations probably increased throughout the region. In the future, however, changes in the quality of its breeding habitat (Sillett et al. 2000 Sillett, T. S., R. T. Holmes and T. W. Sherry. (2000). Impacts of a global climate cycle on population dynamics of a migratory songbird. Science 288:2040-2042. Close , Rodenhouse et al. 2003 Rodenhouse, N. L., T. S. Sillett, P. J. Doran and R. T. Holmes. (2003). Multiple density-dependence mechanisms regulate a migratory bird population during the breeding season. Proc. R. Soc. Lond. B. 270:2105-2110. Close , Sillett and Holmes 2005 Sillett, T. S. and R. T. Holmes. (2005). "Long-term demographic trends, limiting factors, and the strength of density dependence in a breeding population of a migratory songbird." In Birds of Two Worlds: Advances in the Ecology and Evolution of Temperate-Tropical Migration Systems., edited by R. Greenberg and P. P. Marra, 426-436. Baltimore, MD: Johns Hopkins University Press. Close , Holmes 2011 Holmes, R. T. (2011). Avian population and community processes in forest ecosystems: Long-term research in the Hubbard Brook Experimental Forest. Forest Ecology and Management 262 (1):20-32. Close ), overwintering habitat (Holmes 2007 Holmes, R. T. (2007). Understanding population change in migratory songbirds: Long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (2):2-13. Close , see also Studds and Marra 2007 Studds, C. E. and P. P. Marra. (2007). Linking fluctuations in rainfall to nonbreeding season performance in a long-distance migratory bird, Setophaga ruticilla. Climate Research 35 (1-2):115-122. Close , Studds and Marra 2011 Studds, C. E. and P. P. Marra. (2011). Rainfall-induced changes in food availability modify the spring departure programme of a migratory bird. Proceedings of the Royal Society B-Biological Sciences 278 (1723):3437-3443. Close ), and enhanced risks during migration (Sillett and Holmes 2002 Sillett, T. S. and R. T. Holmes. (2002). Variation in survivorship of a migratory songbird throughout its annual cycle. Journal of Animal Ecology 71:296-308. Close ) could reverse that trend. Climate change is another factor potentially affecting the distribution and abundance of this species (Matthews et al. 2011 Matthews, S. N., L. R. Iverson, A. M. Prasad and M. P. Peters. (2011). Changes in potential habitat of 147 North American breeding bird species in response to redistribution of trees and climate following predicted climate change. Ecography 34 (6):933-945. Close ), but thus far, the species seems able to adjust to warming temperatures (Kaiser et al. 2014 Kaiser, S. A., T. S. Sillett and M. S. Webster. (2014). Phenotypic plasticity in hormonal and behavioural responses to changes in resource conditions in a migratory songbird. Animal Behaviour 96:19-29. Close , Townsend et al. 2013 Townsend, A. K., T. S. Sillett, N. K. Lany, S. A. Kaiser, N. L. Rodenhouse, M. S. Webster and R. T. Holmes. (2013). Warm springs, early lay dates, and double brooding in a North American migratory songbird, the Black-throated Blue Warbler. PLOS One 8 (4):e59467. Close , Townsend et al. 2016 Townsend, A. K., E. G. Cooch, T. S. Sillett, N. L. Rodenhouse, R. T. Holmes and M. S. Webster. (2016). The interacting effects of food, spring temperature, and global climate cycles on population dynamics of a migratory songbird. Global Change Biology 22 (2):544-555. Close , Lany et al. 2016 Lany, N. K., M. P. Ayres, E. E. Stange, T. S. Sillett, N. L. Rodenhouse and R. T. Holmes. (2016). Breeding timed to maximize reproductive success for a migratory songbird: The importance of phenological asynchrony. Oikos 125 (5):656-666. Close ).

The Black-throated Blue Warbler is one of the most intensively studied migratory passerine species in North America, and research on its populations has led to a number of conceptual advances. It is one of the few migratory songbirds for which the demography of populations has been examined in both breeding and overwintering areas. Most of these studies have focused on the factors and processes that limit and/or regulate populations and where they operate; for example, in breeding and non-breeding seasons (see reviews by Holmes 2007 Holmes, R. T. (2007). Understanding population change in migratory songbirds: Long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (2):2-13. Close , Holmes 2011 Holmes, R. T. (2011). Avian population and community processes in forest ecosystems: Long-term research in the Hubbard Brook Experimental Forest. Forest Ecology and Management 262 (1):20-32. Close ; Demography: Population Regulation and Limitation). In addition, survivorship has been assessed for oversummer (May–August), overwinter (October–March), and migratory periods (Sillett and Holmes 2002 Sillett, T. S. and R. T. Holmes. (2002). Variation in survivorship of a migratory songbird throughout its annual cycle. Journal of Animal Ecology 71:296-308. Close ), which is unique for any migratory passerine. Also, the connectivity between breeding and overwintering sites for individuals and populations has been examined through analyses of stable-isotope ratios in warbler tissues, mainly feathers (Chamberlain et al. 1997 Chamberlain, C. P., J. D. Blum, R. T. Holmes, X. Feng, T. W. Sherry and G. R. Graves. (1997). The use of isotope tracers for identifying populations of migratory birds. Oecologia 109 (1):132-141. Close , Rubenstein et al. 2002 Rubenstein, D. R., C. P. Chamberlain, R. T. Holmes, M. P. Ayres, J. R. Waldbauer, G. R. Graves and N. C. Tuross. (2002). Linking breeding and wintering ranges of a Neotropical migrant songbird using table isotopes. Science 295:591-593. Close , Graves et al. 2002 Graves, G. R., C. S. Romanek and A. R. Navarro. (2002). Stable isotope signature of philopatry and dispersal in a migratory songbird. Proceedings of the National Academy of Sciences of the United States of America 99:8096-8100. Close , Bearhop et al. 2004 Bearhop, S., G. M. Hilton, S. C. Votier and S. Waldron. (2004). Stable isotope ratios indicate that body condition in migrating passerines is influenced by winter habitat. Proc. Royal Soc. Lond. B 271:S215-S218. Close ) and recently with geolocators (M. T. Hallworth, unpublished data).

Many other aspects of the species’ natural history, ecology, and behavior have been studied in varying amounts of detail, including population fluctuations and regional synchrony in breeding areas (Holmes and Sherry 2001 Holmes, R. T., and T. W. Sherry (2001). Thirty-year bird population trends in an unfragmented temperate deciduous forest: importance of habitat change. Auk 118: 589–609. Close , Jones et al. 2003b Jones, J., P. J. Doran and R. T. Holmes. (2003b). Climate and food synchronize regional forest bird abundances. Ecology 84:3024-3032. Close ), range-wide age-ratios (Graves 1997b Graves, G. R. (1997b). Geographic clines of age ratios of Black-throated Blue Warblers (Dendroica caerulescens). Ecology 78:2524-2531. Close ), breeding habitat use and nest-site selection (Steele 1992 Steele, B. B. (1992). Habitat selection by breeding Black-throated Blue Warblers (Dendroica caerulescens) at two spatial scales. Ornis Scandinavica 23:33-42. Close , Steele 1993 Steele, B. B. (1993). Selection of foraging and nesting sites by Black-throated Blue Warblers: their relative influence on habitat choice. Condor 95:568-579. Close , Holmes et al. 1995 Holmes, R. T., P. P. Marra and T. W. Sherry. (1995). Habitat-specific demography of breeding Black-throated Blue Warblers (Dendroica caerulescens): implications for population dynamics. Journal of Animal Ecology 65:183-195. Close , Hahn and Silverman 2007 Hahn, B. A. and E. D. Silverman. (2007). Managing breeding forest songbirds with conspecific song playbacks. Animal Conservation 10 (4):436-441. Close , Betts et al. 2008a Betts, M. G., A. S. Hadley, N. Rodenhouse and J. J. Nocera. (2008a). Social information trumps vegetation structure in breeding-site selection by a migrant songbird. Proceedings of the Royal Society B-Biological Sciences 275 (1648):2257-2263. Close , Betts et al. 2008b Betts, M. G., N. L. Rodenhouse, T. S. Sillett, P. J. Doran and R. T. Holmes. (2008b). Dynamic occupancy models reveal within-breeding season movement up a habitat quality gradient by a migratory songbird. Ecography 31 (5):592-600. Close , Goetz et al. 2010 Goetz, S. J., D. Steinberg, M. G. Betts, R. T. Holmes, P. J. Doran, R. Dubayah and M. Hofton. (2010). Lidar remote sensing variables predict breeding habitat of a Neotropical migrant bird. Ecology 91 (6):1569-1576. Close ), foraging behavior and ecology (Holmes et al. 1979b Holmes, R. T., R. E. Bonney Jr., and S. W. Pacala. (1979b). Guild structure of the Hubbard Brook bird community: a multivariate approach. Ecology 60:512-520. Close , Holmes and Robinson 1981 Holmes, R. T. and S. K. Robinson. (1981). Tree species preferences of foraging insectivorous birds in a northern hardwood forest. Oecologia 48:31-35. Close , Robinson and Holmes 1982 Robinson, S. K., and R. T. Holmes (1982). Foraging behavior of forest birds: the relationships among search tactics, diet, and habitat structure. Ecology 63:1918–1931. Close , Robinson and Holmes 1984 Robinson, S. K. and R. T. Holmes. (1984). Effects of plant species and foliage structure on the foraging behavior of forest birds. Auk 101:672-684. Close , Holmes 1986 Holmes, R. T. (1986). Foraging patterns of forest birds: male-female differences. Wilson Bulletin 98: 196–213. Close , Holmes and Schultz 1988 Holmes, R. T. and J. C. Schultz. (1988). Food availability for forest birds: effects of prey distribution and abundance on bird foraging. Canadian Journal of Zoology 66:720-728. Close ), mating systems and paternity (Chuang et al. 1999 Chuang, H. C., M. S. Webster and R. T. Holmes. (1999). Extrapair paternity and local synchrony in the Black-throated Blue Warbler. Auk 116:726-736. Close , Chuang-Dobbs et al. 2001a Chuang-Dobbs, H. C., M. S. Webster and R. T. Holmes. (2001a). Paternity and parental care in the Black-throated Blue Warbler, Dendroica caerulescens. Animal Behaviour 62:83-92. Close , Chuang-Dobbs et al. 2001b Chuang-Dobbs, H. C., M. S. Webster and R. T. Holmes. (2001b). The effectiveness of mate guarding by male Black-throated Blue Warblers. Behavioral Ecology 12:541-546. Close , Webster et al. 2001 Webster, M. S., H. C. Chuang-Dobbs and R. T. Holmes. (2001). Microsatellite identification of extrapair sires in a socially monogamous warbler. Behavioral Ecology 12:439-446. Close , Kaiser et al. 2014 Kaiser, S. A., T. S. Sillett and M. S. Webster. (2014). Phenotypic plasticity in hormonal and behavioural responses to changes in resource conditions in a migratory songbird. Animal Behaviour 96:19-29. Close , Kaiser et al. 2015 Kaiser, S. A., T. S. Sillett, B. B. Risk and M. S. Webster. (2015). Experimental food supplementation reveals habitat-dependent male reproductive investment in a migratory bird. Proceedings of the Royal Society B-Biological Sciences 282 (1803). Close , Kaiser et al. 2017a Kaiser, S. A., B. B. Risk, T. S. Sillett and M. S. Webster. (2017a). Ecological and social factors constrain spatial and temporal opportunities for mating in a migratory songbird. American Naturalist 189 (3):283-296. Close , Cline et al. 2016 Cline, M. H., J. L. Hatt, M. J. Conroy and R. J. Cooper. (2016). Experimental evidence for a phenotypic trait as an age-dependent intrasexual social signal between familiar individuals. Animal Behaviour 111:319-327. Close ), sex-ratio bias (K. Grabenstein, MSW, unpublished data), and parental care (Stodola et al. 2009 Stodola, K. W., E. T. Linder, D. A. Buehler, K. E. Franzreb and R. J. Cooper. (2009). Parental care in the multi-brooded Black-throated Blue Warbler. Condor 111 (3):497-502. Close , Stodola et al. 2010 Stodola, K. W., E. T. Linder, D. A. Buehler, K. E. Franzreb, D. H. Kim and R. J. Cooper. (2010). Relative influence of male and female care in determining nestling mass in a migratory songbird. Journal of Avian Biology 41 (5):515-522. Close , Kaiser et al. 2014 Kaiser, S. A., T. S. Sillett and M. S. Webster. (2014). Phenotypic plasticity in hormonal and behavioural responses to changes in resource conditions in a migratory songbird. Animal Behaviour 96:19-29. Close ). Another extensive line of research has considered how this species responds to, and is affected by, environmental change, including that brought about by forest management practices (e.g., Bourque and Villard 2001 Bourque, J. and M. A. Villard. (2001). Effects of selection cutting and landscape-scale harvesting on the reproductive success of two neotropical migrant bird species. Conservation Biology 15 (1):184-195. Close , Harris and Reed 2001 Harris, R. J. and J. M. Reed. (2001). Territorial movement of Black-throated Blue Warblers in a landscape fragmented by forestry. Auk 112:544-549. Close , Harris and Reed 2002b Harris, R. J. and J. M. Reed. (2002b). Effects of forest-clearcut edges on a forest-breeding songbird. Canadian Journal of Zoology 80:1026-1037. Close , Harris and Reed 2002a Harris, R. J. and J. M. Reed. (2002a). Behavioral barriers to non-migratory movements of birds. Annales Zoologici Fennici 39:275-290. Close , Jones et al. 2003b Jones, J., P. J. Doran and R. T. Holmes. (2003b). Climate and food synchronize regional forest bird abundances. Ecology 84:3024-3032. Close , Betts et al. 2007 Betts, M. G., G. J. Forbes and A. W. Diamond. (2007). Thresholds in songbird occurrence in relation to landscape structure. Conservation Biology 21 (4):1046-1058. Close , Cornell and Donovan 2010a Cornell, K. L. and T. M. Donovan. (2010a). Effects of spatial habitat heterogeneity on habitat selection and annual fecundity for a migratory forest songbird. Landscape Ecology 25 (1):109-122. Close , Cornell and Donovan 2010b Cornell, K. L. and T. M. Donovan. (2010b). Scale-dependent mechanisms of habitat selection for a migratory passerine: An experimental approach. Auk 127 (4):899-908. Close , Chandler et al. 2012 Chandler, C. C., D. I. King and R. B. Chandler. (2012). Do mature forest birds prefer early-successional habitat during the post-fledging period? Forest Ecology and Management 264:1-9. Close , Hache et al. 2013 Hache, S., T. Petry and M.-A. Villard. (2013). Numerical response of breeding birds following experimental selection harvesting in northern hardwood forests. Avian Conservation and Ecology 8 (1). Close ), invasive species (Stodola et al. 2013 Stodola, K. W., E. T. Linder and R. J. Cooper. (2013). Indirect effects of an invasive exotic species on a long-distance migratory songbird. Biological Invasions 15 (9):1947-1959. Close ), and a changing climate (Rodenhouse 1992 Rodenhouse, N. L. (1992). Potential effects of climatic change on migrant land birds: a simulation model. Conservation Biology 6:263-272. Close , Rodenhouse et al. 2008a Rodenhouse, N. L., S. N. Matthews, K. P. McFarland, J. D. Lambert, L. R. Iverson, A. Prasad, T. S. Sillett and R. T. Holmes. (2008a). Potential effects of climate change on birds of the Northeast. Mitigation and Adaptation Strategies for Global Change 13 (5-6):517-540. Close , Rodenhouse et al. 2009 Rodenhouse, N. L., L. M. Christenson, D. Parry and L. E. Green. (2009). Climate change effects on native fauna of northeastern forests. Canadian Journal of Forest Research 39 (2):249-263. Close , Townsend et al. 2013 Townsend, A. K., T. S. Sillett, N. K. Lany, S. A. Kaiser, N. L. Rodenhouse, M. S. Webster and R. T. Holmes. (2013). Warm springs, early lay dates, and double brooding in a North American migratory songbird, the Black-throated Blue Warbler. PLOS One 8 (4):e59467. Close , Townsend et al. 2016 Townsend, A. K., E. G. Cooch, T. S. Sillett, N. L. Rodenhouse, R. T. Holmes and M. S. Webster. (2016). The interacting effects of food, spring temperature, and global climate cycles on population dynamics of a migratory songbird. Global Change Biology 22 (2):544-555. Close , Kaiser et al. 2014 Kaiser, S. A., T. S. Sillett and M. S. Webster. (2014). Phenotypic plasticity in hormonal and behavioural responses to changes in resource conditions in a migratory songbird. Animal Behaviour 96:19-29. Close , Lany et al. 2016 Lany, N. K., M. P. Ayres, E. E. Stange, T. S. Sillett, N. L. Rodenhouse and R. T. Holmes. (2016). Breeding timed to maximize reproductive success for a migratory songbird: The importance of phenological asynchrony. Oikos 125 (5):656-666. Close ).

The extensive knowledge about the ecology and behavior of this species contributes to understanding of the factors and processes that affect the distribution and abundance of migratory passerines in general, and thus, to their conservation. However, much remains to be learned about its life history, population ecology, and responses to a changing environment.