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Cerulean Warbler Dendroica cerulea

Justification
This species is listed as Vulnerable, because its population is estimated to have undergone a rapid decline owing to continuing habitat loss and fragmentation on its breeding and wintering grounds.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: #http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls#.
SACC. 2006. A classification of the bird species of South America. Available at: #http://www.museum.lsu.edu/~Remsen/SACCBaseline.html#.

Identification
12 cm. Small canopy-dwelling wood-warbler. Male has sky-blue upperparts, with two white wing-bars. Underparts are mostly white with a narrow blue breast band and flank streaks. Female plumage mirrors that of the male but the blue is replaced by a greenish-blue. Voice Song is a high-pitched rather musical buzz.

Distribution and population
Dendroica cerulea breeds from Quebec and Ontario (Canada), east to Nebraska and south to northern Texas, Louisiana, Mississippi, Alabama and Georgia (USA) (A.O.U. 1983). A four year study from 1997-2000 identified several seemingly key sites that support large populations (Rohrbaugh et al. 2001). These included the Cumberland Mountains north-west of Knoxville, Tennessee; the Montezuma wetlands complex and adjacent areas in central New York; the Kaskaskia River Valley and Shawnee National Forest in south eastern Illinois; Big Oaks National Wildlife Refuge (formerly Jefferson Proving Ground), Morgan-Monroe and Yellowwood state forests, and Hoosier National Forest of southern Indiana (Register and Islam 2008); Queens University Biological Station in south eastern Ontario; the Kalamazoo River of south western Michigan; the Eleven Point and Upper Current rivers in Missouri; the Shenendoah National Park and Blue Ridge Highway in western Virginia; and the Delaware River Valley and adjacent highlands of north western New Jersey. These areas may represent primary areas for population monitoring and conservation (Rohrbaugh et al. 2001). It migrates south through the south-eastern USA, the Bahamas, Cuba, Jamaica, the Caribbean slope of Mexico, Belize, Guatemala, Honduras, Costa Rica and Panama, and winters from Colombia and Venezuela south, mainly east of the Andes, to eastern Ecuador, south-eastern Peru and perhaps occasionally to northern Bolivia (A.O.U. 1983, Herzog et al. 2009). Breeding Bird Survey results show declines equating to 26% per decade over the period 1980-2002, but longer-term declines are even more severe (Sauer et al. 2003).

Population justification
Rich et al. (2003).

Trend justification
This species has undergone a large and statistically significant decrease over the last 40 years in North America (-83% decline over 40 years, equating to a -35.8% decline per decade; data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007).

Ecology
Breeds in mature deciduous forest (A.O.U. 1983, Sibley and Monroe 1990), often in the vicinity of swamps (Curson et al 1994). Birds preferentially locate territories in forests with higher canopy height, greater canopy cover (c. 85%) and larger trees (Roth and Islam 2008). Wintering birds are found in Andean submontane forest, mainly between 1,000 and 2,000 m (Curson et al. 1994). Traditional shade coffee plantations are an important wintering habitat supporting densities of cerulean warblers 3-14 times higher  than those of neighbouring primary forest (Bakermans et al. 2009). Migrating birds are recorded from a variety of forest woodland, secondary growth and scrub habitats (A.O.U. 1983). and dead birds have been found in páramo at 3550 m around Laguna de Mucubají, Mérida (Rengifo et al. 2005). The nest is built on the branch of a tree, and breeding takes place between May and July (Curson et al. 1994).

Threats
Degradation of habitat through land use change is the major threat to this species. Conversion of mature deciduous forest to agricultural or urban areas, fragmentation and increasing isolation of remaining mature deciduous forest, the change to shorter rotation periods and even-aged management, and loss of key tree species to disease are all breeding season constraints (Hamel 2000). Mountaintop mining constitutes a known but as yet uncontrolled threat on the breeding grounds, primarily in West Virginia, Virginia, Tennessee and Kentucky (G. Butcher in litt. 2003). Wintering habitat is also threatened by conversion to other land uses such as pastureland, subsistence crops and coffee plantations, and is converted into coca plantations which have a detrimental effect on suitable primary forest habitat. Conversion from shade to sun coffee reduces habitat quality for cerulean warblers; Colombia has converted 70% of its plantations, while Venezuela lost 38% of its plantations between 1950 ansd 1990 (Bakermans et al. 2009). Attempts to eradicate coca plantations will also potentially damage forests (Hamel 2000). 

Conservation Actions Underway
It is listed as a species of concern on the U. S. Fish and Wildlife Service website where full details of the species's status and conservation actions are listed. Current activities include planning projects that use estimates of minimum tract size for the species as criteria for habitat acquisition and protection, land protection and acquisition projects to increase the amount of forest in certain areas such as the Interior Low Plateaus and Coastal Plain of Tennessee, and the Cerulean Warbler Atlas Project, an information gathering project managed by Cornell Laboratory of Ornithology (Hamel 2000). A symposium was held in 2006 to address the species's conservation (Dawson 2006), followed by a summit in 2007 focussing on the development and implementation of conservation actions (Anon 2007). A reserve was created specifically for the species in Colombia managed by ProAves Colombia, the first reserve in South America specifically for a neotropical migrant landbird. Shade grown coffee is promoted as Cerulean warbler friendly. Over 1 million acres of bottomland forest in the USA have been replanted with native hardwoods. Conservation Actions Proposed
Understand fully the requirements of the species in terms of ideal or high quality breeding habitat. Develop and test forest-stand management techniques that result in "ideal" or "high quality" habitat. Protect intact primary forest ecosystems to maintain wintering populations. Prevent the conversion of shade coffee agroecosystems (which support high densities of wintering Cerulean warblers) into cattle lands (C. Rengifo in litt. 2012). Urgently protect key sites for the species in its breeding and non-breeding range. Conduct thorough environmental impact assessment prior to any mining operations to ensure that measures are taken to avoid destroying habitat and to mitigate against any negative impacts.

Related state of the world's birds case studies

References
Anon. 2007. Cerulean Warbler summit 2: Development and implementation of Conservation Actions.

AOU. 1983. Check-list of North American birds. American Ornithologists' Union, Washington, D C.

Bakermans, M. H.; Vitz, A. C.; Rodewald, A. D.; Rengifo, C. G. 2009. Migratory songbird use of shade coffee in the Venezuelan Andes with implications for conservation of Cerulean Warbler. Biological Conservation 142: 2476-2483.

Curson, J.; Quinn, D.; Beadle, D. 1994. New World warblers. A&C Black/Christopher Helm, London.

Dawson, D. K.; Laurel, M. D. 2006. A proactive approach to Cerulean Warbler conservation. Wings without borders: IV North American Ornithological Conference, October 3-7, 2006, Veracruz, Mexico, pp. 76. American Ornithologists' Union, Waco, TX, USA.

Hamel, P.B. 2000. Cerulean warbler. Birds of North America 511: 1-20.

Herzog, S. K.; García-Soliz, V. H.; Davis, S. E. 2009. Status of the Cerulean Warbler (Dendroica cerulea) at the southern terminus of its non-breeding range, with a review of other nearctic-neotropical migrant Parulidae in Bolivia. Ornitologia Neotropical 20(1): 121-130.

Register, S.; Islam, K. 2008. Effects of silvicultural treatments on Cerulean Warbler (Dendroica cerulea) abundance in southern Indiana. Forest Ecology and Management 255: 3502-3505.

Rengifo, C.; Nava, A.; Zambrano , M. 2005. Lista de Aves de La Mucuy y Mucubají, Parque Nacional Sierra Nevada, Mérida, Venezuela. Editorial Venezolana, Mérida, Venezuela.

Rich, T.D.; Beardmore, C.J.; Berlanga, H.; Blancher, P.J.; Bradstreet, M.S.W.; Butcher, G.S.; Demarest, D.W.; Dunn, E.H.; Hunter, W.C.; Inigo-Elias, E.E.; Martell, A.M.; Panjabi, A.O.; Pashley, D.N.; Rosenberg, K.V.; Rustay, C.M.; Wendt, J.S.; Will, T.C.

Rohrbaugh, R. W.; Barker, S. E.; Rosenberg, K. V. 2001. Little Blue Warblers. Birdscope 15: 1-3.

Roth, K. L.; Islam, K. 2008. Habitat selection and reproductive success of Cerulean Warblers in Indiana. Wilson Journal of Ornithology 120(1): 105-110.

Salaman, P. 2005. Latin welcome for the Cerulean Warbler. Bird Conservation: 6.

Sauer, J. R.; Hines, J. E.; Fallon, J. 2003. The north American breeding bird survey, results and analysis 1966-2002. version 2003.1.

Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Further web sources of information
Audubon WatchList

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Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Bird, J., Harding, M., O'Brien, A., Sharpe, C J

Contributors
Butcher, G., Sharpe, C J, Rengifo, C., Islam, K.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Dendroica cerulea. Downloaded from http://www.birdlife.org on 24/11/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/11/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Cerulean warbler (Dendroica cerulea)

Key facts
Current IUCN Red List category Vulnerable
Family Parulidae (New World warblers)
Species name author (Wilson, 1810)
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 815,000 km2
Country endemic? No
Links to further information
- Additional Information on this species