Cerulean Warblers use two distinct habitats in New York. One type is dry oak-hickory dominated ridegtops and side-slopes. The other is riparian forests or forested swamps with maple, ash, and sycamore trees.
Although Cerulean Warblers have expanded their distribution in New York since the early 1900s (Lindsay 1998), they have exhibited widespread population declines (Sauer et al. 2013) and the trend in increasing distribution for New York has recently ceased (McGowan and Corwin 2008). Many populations in New York occur on protected land where management can be tailored to this warbler's needs; however, maintaining landscapes with a high composition of forest remains a challenge. Management of forests on private lands can impact populations and requires landowner cooperation to limit fragmentation of mature forests.
Cerulean Warblers exhibited a 13% decline in breeding distribution throughout New York State between the first (1980-85) and second (2000-2005) Breeding Bird Atlas surveys (McGowan and Corwin 2008). The largest declines were in the Great Lakes Plains and the Appalachian Plateau, both strongholds for the species in the state (McGowan and Corwin 2008). Data from the Breeding Bird Survey are not sufficient to assess population trends for New York (Sauer et al. 2013); however, trends from the northeastern region showed stability or patchy local declines and increases from 1990-1999 (Bled et al. 2013).
The rangewide breeding distribution of the Cerulean Warbler exhibited a shift to the north in the later part of the 20th century (Bled et al. 2013; Sauer et al. 2013) and concurrently, the distribution in New York increased (Lindsay 1998). It appears that this trend has ceased (McGowan and Corwin 2008) and in fact, some seemingly robust northeastern populations may be sinks (Jones et al. 2004) where nesting success does not compensate for mortality.
Long-term population trends of Cerulean Warblers in New York are unclear. Data from the Breeding Bird Survey are not sufficient to assess trends for New York State, however, region-wide this species has suffered dramatic declines, averaging 3.2% per year from 1966-2011 (Sauer et al. 2013). This equates to a 70% reduction in population numbers (Sauer et al. 2013). This decline has been most profound in the mid-western and core Appalachian parts of the breeding range (Bled et al. 2013; Sauer et al. 2013). The distribution of Cerulean Warblers in New York State has increased since the early 1900s (Lindsay 1998; McGowan and Corwin 2008). Eaton (1910) depicted the distribution as restricted to the Lake Ontario lowlands in central and western New York with dispersed occurrences in the Hudson Valley. In the mid-1900s, Cerulean Warblers expanded into the Appalachian Plateau, Hudson Highlands, and Jefferson and St. Lawrence counties, where a small population resides (Bull 1974; Lindsay 1998; McGowan and Corwin 2008).
Cerulean Warblers face numerous threats on their breeding and wintering grounds including conversion of forest for coffee and cocoa production, forest fragmentation, incompatible forest management practices, and high predation rates (Buehler et al. 2013). Conservation in New York, where Cerulean Warblers breed, focuses on maintaining heavily forested landscapes. Populations in New York largely occur on protected lands where conversion of mature forest is limited. However, forest management on private lands and maintaining heavily forested landscapes surrounding known breeding populations are still of concern (McGowan and Corwin 2008). Wood et al. (2013) developed guidelines for forest management practices that promote habitat for this species within heavily forested landscapes that are available to public land managers and private landowners.
Threats to the persistence of Cerulean Warblers exist in their winter and breeding habitat, as well as during migration (Buehler et al. 2013). Habitat loss is a primary concern. On wintering grounds in the tropics, the clearing of land for coffee and particularly cocoa production are significant threats. In the core of the breeding range in the central Appalachians, threats include mountaintop removal coal mining and hydraulic fracturing. During migration, Cerulean Warblers suffer high mortality from collisions with human structures (Klem 2008). In New York, the largest populations occur on protected lands; however, habitat loss, including incompatible forest management practices and conversion and fragmentation of mature forest, may still pose a threat on private lands (McGowan and Corwin 2008). High nest predation rates are limiting population growth in the Midwest, and even in the Northeast and Appalachian Mountains where nest success is higher, recruitment may not be adequate to compensate for mortality (Buehler et al. 2008). Known nest predators include chipmunks, snakes, and birds; particularly blue jays (Cyanocitta cristata) (Boves and Buehler 2012; Buehler et al. 2013).
Maintaining large blocks of unfragmented mature forest is the primary management considerations for this species, particularly in riparian areas and on uplands and ridgetops with oak-hickory or mixed mesophytic forest. Maintaining heavily forested landscapes surrounding known breeding populations is also a concern (Buehler et al. 2008).
Forest management strategies were recently developed to maintain and enhance habitat for this species in the Appalachian Mountain Bird Conservation Region, which includes much of south central and south western New York (Wood et al. 2013). The recommended management practices are largely based on the results of the Cooperative Cerulean Warbler Forest Management Project, a robust study replicated at seven locations across four Appalachian states within the core of the Cerulean Warbler breeding range. The results of this project suggest that in mature forest with high Cerulean Warbler densities (>5 territories /25 acres) and high nest success, not harvesting is the best option to retain successful breeding populations. The study also found that in actively managed oak forests that exist within a highly forested (>70% with a 6-mile radius) landscape, retaining residual basal areas of ~40-90ft2/acre after harvest creates a forest structure that is generally favorable for Cerulean Warblers. In managed stands, retaining large diameter trees and dominance of white and chestnut oak is important; other important tree species include hickories and sugar maples. Harvest practices have not been tested in landscapes with lower forest cover and recommendations for these areas may differ (Wood et al. 2013).
Maintaining mature forest habitats and landscapes with a high composition of forest is recommended. See conservation and management strategies for specific compatible forest management practices.
Further research is needed to examine the long-term response of Cerulean Warbler populations to varied harvest regimes as well as to study post-fledgling survival in diverse habitats and under different management practices (Buehler et al. 2013). Also, work is needed on the wintering grounds to determine winter survivorship, relative abundance by habitat, and to identify conservation focal areas and threats facing them (Buehler et al. 2013). In New York, a site-specific monitoring program targeting the largest populations statewide is needed (Rosenberg et al. 2000).
Conservation of the largest forest blocks and encouragement of forest regeneration in the lake plain region of New York is a primary concern (NYSDEC 2005). This region supports two of the largest populations of Cerulean Warblers in the state (Rosenberg et al. 2000). Continued fragmentation by human development will likely affect the landscape-level composition of forest which could impact populations, even those on protected lands (NYSDEC 2005).
Cerulean Warblers are found in both riparian and upland forest habitats in New York within landscapes that are heavily forested. They typically inhabit forested wetlands and riparian corridors with a mature canopy composed of sycamore, silver maple, red maple, and green ash, or dry ridgetops and side-slopes with mature oak-hickory or mixed mesophytic forest (Rosenberg et al. 2000). This warbler typically selects mature forest stands with late-successional features such as canopy gaps, a well-developed understory and upper-canopy, and large diameter (>16 in dbh) and super-canopy trees (Wood et al. 2013). The Cerulean Warbler is generally considered an area-sensitive species (Buehler et al. 2013), meaning they are typically found in larger habitat patches, and several studies found that they are sensitive to the amount of forest in the surrounding landscape (Wood et al. 2006; Thompson et al. 2012). Nest microhabitat is typically a lateral limb of a deciduous tree concealed from above by leaves or vines and located in the mid- or upper-canopy (Buehler et al. 2013).
Cerulean Warblers are widely but patchily distributed in the Great Lakes Plain, Appalachian Plateau, Allegany Hills, Hudson Highlands, Berkshire Hills, along the Delaware River, and in the Hudson and Mohawk valleys (McGowan and Corwin 2008). Large populations occur at the Montezuma Wetlands complex and adjacent Galen WMA, Iroquois-Oak Orchard-Tonawanda complex, and in Allegany State Park and vicinity (Rosenberg et al. 2000). Cerulean Warblers appear to have disappeared from Long Island, southern Westchester and Rockland counties, and many sites along the Hudson and Mohawk river valleys since 1985. (McGowan and Corwin 2008).
Cerulean Warblers occur only in eastern North America in summer. Their northern range extent includes southern New England, southern Ontario, and the Great Lakes states. Their distribution continues south through the Appalachian Mountain range and the Mississippi River drainage. Their southern range extent is northern Georgia, Tennessee, and Arkansas (Hamel 2000). They over-winter in broad-leaved evergreen forests of the Andes Mountains within a narrow elevation band (1,600 to 6,000 ft.) from Venezuela to Peru.
The Cerulean Warbler is a small passerine that weighs approximately 8-10 grams. Males are sky blue in color, with a black
The best identifying features are the cerulean blue plumage on their head and back and black "necklace" on males. Males are also white underneath with streaking on their sides. Cerulean Warblers have a relatively short tail, and in all plumages, both sexes display two white wing bars. Females are often difficult to see during the breeding season and are also more difficult to identify. They have a dull bluish-green-grey tinted head and back and a cream-colored eyestripe. Females are yellowish underneath with light dusky streaking on their sides. The male's song is an accelerating series of buzzy notes followed by a longer higher-pitched trill-like note. It is sometimes described as "zee-zee-zee-tititi-zeee". Their song is distinctive but could be confused with Black-throated Blue Warbler, Northern Parula, or Blackburnian Warbler.
The best identifying features for males are the cerulean blue plumage on their head and back and black
Breeding season adults, especially males, are easiest to identify.
Cerulean Warbler males are highly territorial during the breeding season and maintain territories averaging roughly 0.74-2.5 acres (0.3-1.0 ha) in size (Buehler et al. 2013). They tend to exhibit clustered territoriality, meaning that territories occur together in groups rather than evenly distributed within the habitat. It is not clear whether this is due to conspecific attraction, the tendency for individuals of the same species to settle near one another, or to limited availability of quality habitat; there is some evidence that both may be factors (Roth and Islam 2007).
Cerulean Warblers forage by gleaning insects from leaves and twigs usually beginning at the proximal part of a branch and hopping along towards the distal end (Buehler et al. 2013). They forage mostly in the forest canopy at the mid-canopy level (George 2009; Wood and Perkins 2012). They are vigorous singers and often sing from song posts within the canopy or upper-canopy (Barg et al. 2006; George 2009; Wood and Perkins 2012).
Cerulean Warblers are typically monogamous for the breeding season (Buehler et al. 2013) and both males and females may select nest locations (Oliarnyk and Robertson 1996; Boves and Buehler 2012). They raise a single brood but will renest if a nest fails (Hamel 2000).
Cerulean Warblers are insectivores. There are no published studies of their specific diet in New York. Research on this subject is not extensive; however a few studies in other states found that Cerulean Warblers consumed primarily Homoptera and larval Lepidoptera (Howell 1924; Hamel 1992; Sample et al. 1993), as well as Coleoptera and Hymenoptera (Hamel 1992; Sample et al. 1993).
The Cerulean Warbler is present in New York during their spring and summer breeding season and also passes through during migration. The best time to see them is anytime from spring migration through the late summer when their plumage is most recognizable. Males sing most strongly in the spring for the first few weeks after arrival on their breeding grounds in late April to mid-May. The website ebird.org reports high frequencies of Cerulean Warblers on checklists in New York submitted from May 1st through the first two weeks of June (eBird 2013).
The time of year you would expect to find Cerulean Warbler active and reproducing in New York.
Setophaga cerulea (Wilson, 1810)
Based on a phylogenetic review by Lovette et al. (2010), many warblers formerly in the Dendroica genus, including the Cerulean Warbler, were moved to Setophaga (Chesser et al. 2011).
Barg, J. J., D. M. Aiama, J. Jones, R. J. Robertson and K. Yasukawa. 2006. Within-territory habitat use and microhabitat selection by male Cerulean Warblers (Dendroica cerulea). The Auk 123:795-806.
Bled, F., J. Sauer, K. Pardieck, P. Doherty and J. A. Royle. 2013. Modeling Trends from North American Breeding Bird Survey Data: A Spatially Explicit Approach. PloS one 8:e81867.
Boves, T. J. and D. A. Buehler. 2012. Breeding Biology, Behavior, and Ecology of Setophaga cerulea in the Cumberland Mountains, Tennessee. Southeastern Naturalist 11:319-330.
Buehler, D. A., J. J. Giocomo, J. Jones, P. B. Hamel, C. M. Rogers, T. A. Beachy, et al. 2008. Cerulean Warbler Reproduction, Survival, and Models of Population Decline. Journal of Wildlife Management 72:646-653.
Buehler, D. A., P. B. Hamel and T. J. Boves. 2013. Cerulean Warbler (Setophaga cerulea), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/511.
Bull, J. 1974. Birds of New York State. Doubleday, Garden City, NY.
Chesser, R. T., R. C. Banks, F. K. Barker, C. Cicero, J. L. Dunn, A. W. Kratter, et al. 2011. Fifty-second supplement to the American Ornithologists' Union Check-list of North American birds. The Auk 128:600-613.
Eaton, E. H. [online]. 1910. Birds of New York. University of the state of New York.
George, G. A. 2009. Foraging ecology of male Cerulean Warblers and other Neotropical migrants.
Hamel, P. B. 1992. Cerulean warbler, Dendroica cerulea. Pages 385-400 in Migratory nongame birds of management concern in the North-east. U.S. Fish Wildl. Serv., Newton Corner, MA.
Hamel, P. B. 2000. Cerulean Warbler Status Assessment. U.S. Fish and Wildlife Service.
Howell, A. 1924. Birds of Alabama. Bureau of Biological Survey. US Department of Agriculture and Department of Game and Fisheries, Brown Printing Company, Montgomery, Alabama.
Jones, J., J. J. Barg, T. S. Sillett, M. L. Veit, R. J. Robertson and A. N. Powell. 2004. Minimum estimates of survival and population growth for Cerulean Warblers (Dendroica cerulea) breeding in Ontario, Canada. The Auk 121:15-22.
Klem, D. [online]. 2008. Avian mortality at windows: the second largest human source of bird mortality on earth. Pp. 244-251 in Proceedings fourth international partners in flight conference.
Lindsay, P. J. 1998. Cerulean Warbler. Pp. 478-480 in Bull's Birds of New York State, (E. Levine, ed.). Comstock Publishing Associates, Ithaca, NY.
Lovette, I. J., J. L. Pérez-Emán, J. P. Sullivan, R. C. Banks, I. Fiorentino, S. Córdoba-Córdoba, et al. 2010. A comprehensive multilocus phylogeny for the wood-warblers and a revised classification of the Parulidae (Aves). Molecular Phylogenetics and Evolution 57:753-770.
McGowan, K. J. and K. Corwin. 2008. The Second Atlas of Breeding Birds in New York State. Cornell University Press.
NYSDEC. 2005. Comprehensive Wildlife Conservation Strategy for New York. New York Department of Environmental Conservation.
New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.
Oliarnyk, C. J. and R. J. Robertson. 1996. Breeding behavior and reproductive success of Cerulean Warblers in southeastern Ontario. The Wilson Bulletin:673-684.
Rosenberg, K. V., S. E. Barker and R. W. Rohrbaugh [online]. 2000. An atlas of Cerulean Warbler populations. Cornell Laboratory of Ornithology, Ithaca, New York, New York, USA.
Roth, K. L. and K. Islam. 2007. Do Cerulean Warblers (Dendroica Cerulea) Exhibit Clustered Territoriality? The American Midland Naturalist 157:345-355.
Sample, B. E., R. J. Cooper and R. C. Whitmore. 1993. Dietary shifts among songbirds from a diflubenzuron-treated forest. Condor:616-624.
Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, D. J. Ziolkowski jr. and W. A. Link [online]. 2013. The North American Breeding Bird Survey, Results and Analysis 1966 - 2011. USGS Patuxent Wildlife Research Center, Laurel, MD.
Thompson, F. R., M. B. Robbins and J. A. Fitzgerald. 2012. Landscape-Level Forest Cover is a Predictor of Cerulean Warbler Abundance. The Wilson Journal of Ornithology 124:721-727.
Wood, P. B. and K. A. Perkins. 2012. Behavioral Activities of Male Cerulean Warblers in Relation to Habitat Characteristics. The Wilson Journal of Ornithology 124:497-505.
Wood, P. B., J. Sheehan, P. Keyser, D. Buehler, J. Larkin, A. Rodewald, et al. 2013. Management guidelines for enhancing Cerulean Warbler breeding habitat in Appalachian hardwood forests. American Bird Conservancy, The Plains, VA.
Wood, P. B., S. B. Bosworth and R. Dettmers. 2006. Cerulean Warbler Abundance and Occurrence Relative to Large-Scale Edge and Habitat Characteristics. The Condor 108:154-165.
eBird [online]. 2013. An online database of bird distribution and abundance [web application]. eBird, Cornell Lab of Ornithology, Ithaca, New York. <http://www.ebird.org> (4 December 2013).
This guide was authored by: Kelly A. Perkins
Information for this guide was last updated on: March 25, 2014
Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Setophaga cerulea. Available from: https://guides.nynhp.org/cerulean-warbler/. Accessed May 20, 2019.