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Species Account

Winter Range

Forested mountains of Columbia and Venezuela south on the east slope of the Andes to eastern Peru and northern Bolivia, mainly at elevations between 600 and 1500m.

Breeding Habitat

In the Northeast, Cerulean Warblers inhabit deciduous forests with tall, mature trees, mostly near stream bottoms, along lake and river shores, or on river islands.  In some areas, they are also found in mature forests on dry slopes and ridges.  Common tree species include oaks, maples, sycamore, black locust, elm, and cottonwoods.

Map of Cerulean Warbler Breeding Territory (25019 bytes)

Description

Male: Light blue (cerulean) upperparts and white underparts.  Indistinct black streaking on back and uppertail coverts.   Narrow black necklace on upper breast, with some black streaking on the flanks.   Two white wing bars.
Photograph by Bill Dyer, CLO
Female:  Bluish-green to olive-green upperparts and white to yellowish-white underparts with faint streaking on flanks.   Two white wing bars and a white or yellowish eyebrow stripe.
Juvenile:  Brownish-gray upperparts with pale median crown stripe; white underparts.

Vocalizations

The typical song has three parts--2 or 3 slow buzzy notes, then several rapid buzzy notes without changing pitch, followed by a longer buzzy note on a higher pitch; zray zray zray ze-ze-ze zreeeee.  Some variation may be noted (listen to cassette).  Song is similar to those of the Northern Parula and Black-throated Blue Warbler.

Foraging Strategy

Forages by gleaning, hover-gleaning, and hawking or sallying (takes short flights from a perch to capture flying insects).  Generally takes food from leaf bases and foliage in the canopy of a variety of trees.

Diet

Insectivorous

Behavior and Displays

Males generally sing high up in mature trees; may sing all day early in the breeding season.

Courtship

Unknown

Nesting

Nest site:   Often found on lateral limbs of the midstory and canopy trees in deciduous forests that are located near an open space.  They are generally concealed from above by clumps of leaves from other branches or vines growing alongside the branch supporting the nest.  Often found in oaks.
Nest Height: 30-60 feet above the ground; some nests found as low as 15 feet.
Nest: 
Small, shallow, cup-shaped nest built by the female.  Usually made of bark, weed stalks, fine grasses, lichen, and moss, neatly interwoven.  Lined with fine fibers, moss, and occasionally hair.
Eggs: 
3-5, usually 4.  Oval to short oval.  Creamy, grayish, or greenish-white in color.   Variably marked with brown, usually fine brown spotting, sometimes loosely wreathed at larger end.
Incubation Period: 
Eggs incubated by the female alone; 12-13 days.
Nestling Period:   Young stay in the nest for 9-10 days; fed by both the male and female.
Fledgling Period: 
When the young first fledge they are fed by the parents in lower-level vegetation.  The length of this period is unknown.
Broods: 
One brood per season, will lay a second clutch if nest fails early in the season. 

The final report, "An Atlas of Cerulean Warbler Populations," is now complete and has been submitted to the USFWS.

Cerulean Warbler Atlas Project
Cornell Lab of Ornithology
159 Sapsucker Woods Road
Ithaca,  NY   14850

Phone:  (607) 254-2465
Fax:  (607) 254-2415

e-mail:  forest_birds@cornell.edu

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