Cerulean Warbler Setophaga cerulea Scientific name definitions

This species account is dedicated in honor of Elizabeth T. Rawlings, member of the Cornell Lab of Ornithology's Administrative Board.

This small, canopy-foraging insectivore breeds locally in mature and older deciduous forests with broken canopies across much of the eastern United States, and spends the nonbreeding season also locally in a number of forested habitats in the northern Andes of South America. Sky blue, sky high in the canopy, the Cerulean Warbler is remarkably difficult to study in the field. Among Setophaga, this species forages and nests higher in the canopy, and migrates farther and earlier, than most others. Still, its social system remains poorly understood, and a variety of interesting questions about biology and management await investigation.

Although the Cerulean Warbler was formerly among the most abundant breeding warblers in the Ohio and Mississippi river valleys, its numbers plummeted in the late 1900s. Concern for the future of this species is warranted. Yet even in the face of these steep declines, populations continue to occur across the breadth of the nonbreeding range, and are currently expanding in the northeastern portion of the breeding range.

Spurred by declining populations and concern for the species, several independent teams have recently investigated this warbler on its breeding grounds: in southern Illinois, by the Illinois Natural History Survey, principally Scott Robinson (Vanderah and Robinson 1995 Vanderah, G. C. and S. K. Robinson. (1995). Habitat selection of Cerulean Warblers in Illinois. Paper read at Abstract. Presented at 113th stated meeting, Am. Ornithol. Union, at Cincinnati, Ohio. Close ); in the Cumberland Plateau, Tennessee, by David Buehler and his students at the University of Tennessee (Nicholson 2004 Nicholson, C. P. (2004). Ecology of the Cerulean Warbler in the Cumberland Mountains of east Tennessee. Ph.D. dissertation, University of Tennessee, Knoxville, Knoxville. Close , Beachy 2007 Beachy, T. A. (2007). Cerulean warbler (Dendroica cerulea) breeding ecology and habitat selection, initial response to forest management, and association with anthropogenic disturbances in the Cumberland Mountains of Tennessee. M.Sc. thesis, University of Tennessee, Knoxville, Knoxville. Close , Boves 2011 Boves, T. A. (2011). Multiple responses by Cerulean Warblers to experimental forest disturbance in the Appalachian Mountains. Ph.D. dissertation, University of Tennessee, Knoxville, Knoxville. Close ); in southern Ontario by Raleigh Robertson at Queen's University and his students (Oliarnyk 1996 Oliarnyk, C. J. (1996). Habitat selection and reproductive success in a population of Cerulean Warblers in southeastern Ontario. Master's Thesis, Queen's Univ., Kingston, ON. Close , Veit 1999 Veit, M. L. (1999). A study of population genetic structure and gene flow in Cerulean Warblers (Dendroica cerulea) and the implications for conservation. M.Sc. thesis, Queen's University, Kingston. Close , Jones 2000 Jones, J. (2000). Assessing conservation utility: A case study of the Cerulean Warbler in eastern Ontario. Ph.D. dissertation, Queen's University, Kingston. Close , Barg 2002 Barg, J. J. (2002). Small-scale biological phenomena in a male Neotropical migrant songbird: Space use, habitat use, and behaviour within territories of male Cerulean Warblers. M.Sc. thesis, Queen's University, Kingston. Close , Girvan 2003 Girvan, M. K. (2003). Examining dispersal and migratory connectivity in Cerulean Warblers (Dendroica cerulea) using stable isotope analysis. M.Sc. thesis, Queen's University, Kingston. Close ); in West Virginia, by Petra Wood with the U. S. Geological Survey and her students at West Virginia University (Weakland 2000 Weakland, C. A. (2000). Songbird response to diameter-limit and two-aged timber harvesting on an industrial forest in central West Virginia. Ph.D. dissertation, West Virginia University, Morgantown. Close , Bosworth 2003 Bosworth, S. B. (2003). Cerulean Warbler relative abundance and frequency of occurrence relative to large-scale edge. M.Sc. thesis, West Virginia University, Morgantown. Close , Perkins 2006 Perkins, K. A. (2006). Cerulean Warbler selection of forest canopy gaps. M.Sc. thesis, West Virginia University, Morgantown. Close , McDermott 2007 McDermott, M. E. (2007). Breeding and post-breeding forest bird community dynamics in regenerating clearcuts and two-age harvests in the central Appalachians. M.Sc. thesis, West Virginia University, Morgantown. Close , George 2009 George, G. A. (2009). Foraging ecology of Neotropical migrants, with concentration on male Cerulean Warblers. Ph.D. dissertation, West Virginia University, Morgantown. Close ); in Ohio by Amanda Rodewald and her students at the Ohio State University (Bakermans 2008 Bakermans, M. H. (2008). Demography and habitat use of Cerulean Warbler on the breeding and wintering grounds. Ph.D. dissertation, Ohio State University, Columbus. Close , Newell 2010 Newell, F. (2010). A bird's eye view of the forest: How does canopy openness affect canopy songbirds? M.Sc. thesis, West Virginia University, Morgantown. Close ); in Kentucky on the Daniel Boone National Forest by Jeff Larkin at his students at the University of Kentucky and Indiana University of Pennsylvania (Hartman 2006 Hartman, P. J. (2006). Habitat selection of the Cerulean Warbler in eastern Kentucky. M.Sc. thesis, University of Kentucky, Lexington. Close , White 2008 White, M. (2008). Avian communities response to silvicultural treatments in eastern Kentucky with an emphasis on Cerulean Warbler ecology. M.Sc. thesis, Indiana University of Pennsylvania, Indiana. Close , Evans 2012 Evans, A. (2012). A comparison of Cerulean Warbler nest-patch vegetation characteristics between core and peripheral breeding populations. M.Sc. thesis, Indiana University of Pennsylvania, Indiana. Close ); in Indiana by Kamal Islam and his students at Ball State University (Roth 2004 Roth, K. L. (2004). Cerulean Warbler breeding biology. M.Sc. thesis, Ball State University, Muncie. Close , Jones 2006c Jones, K. C. (2006c). Reproductive biology and nest success of Cerulean Warblers in Indiana. M.Sc. thesis, Ball State University, Muncie. Close , Register 2007 Register, S. M. (2007). Breeding biology and habitat associations of Cerulean Warblers in southern Indiana. M.Sc. thesis, Ball State University, Muncie. Close , MacNeil 2010 MacNeil, M. (2010). Does timber harvesting affect Cerulean Warbler foraging ecology. M.Sc. thesis, Ball State University, Muncie. Close ); and in the lower Mississippi Alluvial Valley, by scientists at the USDA Forest Service, Southern Hardwoods Lab, principally Paul Hamel.

Interest in the little sky blue princess has grown enormously since Hamel (2000), both scientifically and in the popular press (Franzen 2010, Fallon 2011, Universal Studios 2011). As documented population declines continue, a coordinated effort to address urgent unanswered questions of breeding and nonbreeding habitat management coalesced as the Cerulean Warbler Technical Group in 2001. Capitalizing on the existing work of several independent teams (Vanderah and Robinson 1995 Vanderah, G. C. and S. K. Robinson. (1995). Habitat selection of Cerulean Warblers in Illinois. Paper read at Abstract. Presented at 113th stated meeting, Am. Ornithol. Union, at Cincinnati, Ohio. Close , Nicholson and Buehler 1998 Nicholson, C. P. and D. A. Buehler. (1998). Nesting ecology of the Cerulean Warbler in the Cumberland Mountains of Tennessee. Paper read at N. Am. Ornithol. Conference, at St. Louis, MO. Close , Oliarnyk 1996 Oliarnyk, C. J. (1996). Habitat selection and reproductive success in a population of Cerulean Warblers in southeastern Ontario. Master's Thesis, Queen's Univ., Kingston, ON. Close ; Oliarnyk and Robertson 1996 Oliarnyk, C. J. and R. J. Robertson. (1996). Breeding behavior and reproductive success of Cerulean Warblers in southeastern Ontario. Wilson Bulletin 108:673-684. Close ; Jones and Robertson Jones and Robertson 1997 Jones, J. and R. J. Robertson. (1997). Abstract 75: Winter ecology of the Cerulean Warbler in modified Venezuelan landscapes. Paper read at Presented to the 115th stated meeting of the Am. Ornithol. Union, at Minneapolis-St. Paul, MN. Close , Jones and Robertson 1998 Jones, J. and R. J. Robertson. (1998). Cerulean Warblers in Venezuela: winter ecology and habitat use patterns. Paper read at N. Am. Ornithol. Conference, at St. Louis, MO. Close , Hamel 1998a, Hamel et al. 1998a ), the collaboration became stronger and more inclusive as the decade progressed (Hamel et al. 2004). This effort has become a model for species conservation efforts that bring conflicting interests into a common process: as stand-alone meetings, or summits, of the group occurred in Shepherdstown, West Virginia in 2002; Quito, Ecuador in 2005 (http://www.srs.fs.usda.gov/egc/events/conf2005/conf2005.html); Morgantown, West Virginia in 2007 (http://www.srs.fs.usda.gov/egc/events/Summit2_2007/summit2.html); and Bogotá and San Vicente de Chucurí, Colombia in 2008 (http://www.srs.fs.usda.gov/egc/events/Summit3_2008/summit3.html).

Symposia have been organized by members of the group at international and national ornithological meetings in the US: North American Ornithological Conference, Veracruz, Mexico 2006 (http://www.srs.fs.usda.gov/egc/events/NAOC2006/NAOC2006.php); the Neotropical Ornithological Congress in Maturin, Venezuela, in 2007 (http://www.srs.fs.usda.gov/egc/events/NOC2007/NOC2007.html); the combined meeting of the Association of Field Ornithologists, Cooper Ornithological Society, and Wilson Ornithological Society in Kearney, Nebraska in 2011 (http://www.srs.fs.usda.gov/egc/events/Kearney2011/Kearney2011.html); and the Neotropical Ornithological Congress in Cuzco, Peru in 2011 (http://www.srs.fs.usda.gov/egc/events/NOC2011/NOC2011.html), and elsewhere.

Supported by grants from the National Fish and Wildlife Foundation, the efforts of independent groups extant in the 1990s have coordinated into a substantial evaluation of land management practices in the breeding season, and a rigorously constructed and validated predictive model of non-breeding distribution (Barker et al. 2006, Colorado et al. 2008). Results of these studies exist in report form at this time. The effect of the efforts can be seen in the evaluation process conducted by U.S. Fish & Wildlife Service in response to a petition to list the species as Threatened under the Endangered Species Act.

Upon publication of Hamel (2000), a number of environmental groups, concerned about declining numbers of the Cerulean Warbler, filed a petition to list the species as Threatened (Southern Environmental Law Center 2000), which the U. S. Fish and Wildlife Service acknowledged (USFWS 2002). After lengthy delay, a Cerulean Warbler risk assessment and conservation planning workshop was convened in Shepherdstown, West Virginia in 2006 (http://www.fws.gov/midwest/es/soc/birds/cerw/cerw06ra.html) to respond to the issues raised in the petition. Cerulean Warbler Technical Group members constituted the bulk of the participation in that workshop. Results of the workshop formed the basis of the decision not to list the species as Threatened (U.S. Fish and Wildlife Service 2006). Petitioning groups were not pleased with this decision (http://www.birdlife.org/news/news/2006/12/cerulean_warbler.html). The uncertainties involved in the process of arriving at the decision were itemized by Woods and Morey (2008). Conservation actions outlined in two planning documents resulted from the efforts of the Cerulean Warbler Technical Group (U.S. Fish and Wildlife Service Division of Migratory Bird Management Focal Species Program 2007, Fundacion ProAves et al. 2010).