A medium-sized (5 ¼ -6 inches) wood warbler, the male Connecticut Warbler is most easily identified by its olive back, yellow breast, gray head and throat, and conspicuous white eye-ring. The female is similar to the male, but is somewhat duller, particularly on the head and breast. This species may be distinguished from the similar-looking Mourning Warbler (Geothlypis philadelphia) by the fact that the latter species lacks a eye-ring and has (in the male) a large black neck patch. The Connecticut Warbler breeds in a limited area in south-central Canada and the north-central United States. This species is a long-distance migrant, wintering in northern South America. Migrating Connecticut Warblers follow the Mississippi River north in spring, returning south along the Atlantic seaboard. Connecticut Warblers breed in a number of semi-open woodland habitats, including deciduous forests and bogs with spruce and tamarack trees. In winter, this species inhabits clearings and edges of humid tropical forests. Connecticut Warblers primarily eat small invertebrates, such as insects and spiders, but may also eat fruits and berries. Due to this species’ preference for heavily vegetated habitats, Connecticut Warblers are much more easily heard than seen. Birdwatchers may listen for this species’ “chip-chup-ee” song, or may attempt to observe it foraging for insects deep in the undergrowth. Connecticut Warblers are primarily active during the day, but, like many migratory songbirds, this species migrates at night.
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Breeding
Regularity: Regularly occurring
Type of Residency: Breeding
Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) BREEDING: east-central British Columbia across southern Canada to west-central Quebec, south to southern Manitoba, northern Minnesota, northern Wisconsin, central Michigan, and south-central Ontario. MIGRATION: Rare autumn transient through the eastern West Indies (and most notably on Bermuda) and through northern Venezuela and northeastern Colombia; western and central Venezuela, northern and eastern Colombia, western and central Amazonian Brazil, and southeastern Peru (Ridgely and Tudor 1989). WINTER: Winter range poorly known, since small population is spread over large area. Winters in northern South America, primarily east of the Andes around the Amazon basin (Pitocchelli et al. 1997). Noted rarely in spring as a transient through northern South America and Panama.
Length: 15 cm
Weight: 15 grams
Habitat and Ecology
Comments: Breeds in spruce and tamarack bogs, dry ridges, poplar and aspen woods, moist areas with low shrubby growth, thick undergrowth, or sapling thickets. In thickets of low wet woods or wet meadows in migration. (Terres 1980, Harrison 1978). NON-BREEDING: woodland, forest borders, shrubby clearings (Ridgely and Tudor 1989). BREEDING: Nests on ground, in small hollow, on moss mound in bog, or in grasses or weeds, or at base of shrub (Harrison 1978).
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
Spring migration in North America is chiefly west of the Appalachians. Migrates mostly through West Indies. Present in South America mostly October-April (Ridgely and Tudor 1989).
Comments: Eats insects and spiders obtained from cracks and crevices of bark; feeds on or near ground (Terres 1980).
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 81 to >300
100,000 to >1,000,000 individuals
Comments: Generally uncommon and local on breeding grounds (Flack 1976, DeGraaf et al. 1991). Densities in open spruce woodlands in Minnesota ranged from 2.9-5.6 pairs per hectare; densities in closed spruce forests lower, 1.7-2.7 pairs per hectare (Niemi and Hanowski 1984). Mean numbers on Breeding Bird Survey routes in Manitoba, Saskatchewan, and Wisconsin were 19.3, 11.4, and 9.7 respectively (Price et al. 1995). These latter densities would suggest a minimum population size in the hundreds of thousands.
Life History and Behavior
Eggs are laid in June. Clutch size: 3-5.
Molecular Biology and Genetics
Barcode data: Oporornis agilis
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Oporornis agilis
Public Records: 3
Specimens with Barcodes: 4
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N4B - Apparently Secure
Rounded National Status Rank: N3B - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
Reasons: Widespread in the breeding season, but there is evidence of ongoing declines. Possible threats not well understood. Forest conversion to agriculture is continuing along southern edge of boreal forest in western Canada.
Global Short Term Trend: Decline of 10-30%
Comments: Breeding Bird Survey data indicate a significant population decline of 3.1 percent per year for the period 1980-2000 (n=71, p=0.02; Sauer et al. 2001). In Canada, the rate of decline is averaging 3.4 percent per year (n=43, p=0.02), but in the U.S. no trend is apparent (n=28). These data should be viewed with some caution, since there are relatively few routes that report this species, and densities are low on many routes.
Global Long Term Trend: Decline of 30-50%
Comments: Rangewide, Breeding Bird Survey data for 1966-2000 indicate an average annual decline of 1.9 percent (n=87, p=0.06), but these data should be used with some caution (see above; Sauer et al. 2001).
Degree of Threat: Medium
Comments: HABITAT LOSS/DEGRADATION: Few data, needs study (Pitocchelli et al. 1997). Much of the core of this species' range is in the western boreal forest, so is threatened by forest conversion to agriculture along the southern edges of the boreal zone. In Saskatchewan alone, 4368 square kilometers of forest was lost to agriculture in the period 1966-1994, a rate of -0.87%/year (Hobson et al. 2002). Much of the remaining southern boreal forest in western Canada has been leased to forestry companies (Cummings et al. 1994, Stelfox 1995). May be suffering from habitat loss on wintering grounds (Rappole 1995).
COLLISIONS: Many reports of migrants striking buildings, lighthouses, or towers (Pitocchelli et al. 1997); in Wisconsin, 300 birds were reported killed in this fashion in one season, 140 in one night in Eau Claire (Robbins 1991).
Biological Research Needs: This is one of the poorest known birds in North America. Any studies on its general biology would be valuable contributions; the highest priority is a thorough study of its biology on the breeding grounds (Pitocchelli et al. 1997).
These medium-sized warblers measure 13–15 cm (5.1–5.9 in) in length, with a 22–23 cm (8.7–9.1 in) wingspan. Connecticut warblers weigh 10 g (0.35 oz) when they fledge, attaining an average weight of around 15 g (0.53 oz) as adults. However, birds preparing for migration pack on more weigh to survive the strenuous journey and can weigh up to 25 g (0.88 oz). This species has light yellow underparts and olive upperparts; they have a light eye ring, pink legs, a long tail, pale wing bars and a thin pointed bill. Males have a grey hood; female and immatures are more brown and have a whitish throat.
Their breeding habitat is bogs or open deciduous woods near water, especially with poplar or aspen, in central Canada and states bordering the Great Lakes. The nest is an open cup well-concealed in moss or a clump of grass.
These birds migrate to the Amazon River area in South America in winter. Connecticut warblers undertake different migratory routes in spring and in fall, an atypical behavior. In spring, they normally pass through the Midwest and only rarely vagrating to the East Coast, but in fall, larger numbers of migrating birds move through the East Coast.
They forage on the ground, picking among dead leaves, or hop along branches. These birds mainly eat insects and similar small invertebrates but will supplement their diet occasionally with seeds and berries. They are "skulking" birds that usually spend their time foraging within dense, low vegetation. Such behavior often renders them difficult to see well.
The song of this bird is a loud repeated cheepa-cheepa. The call is a nasal pitch.
Despite its name, this bird would probably only visit Connecticut during migration. They are fairly elusive birds, but it appears that their numbers may be declining due to loss of winter habitat.
Most classification systems consider the genus to be monotypic, with Connecticut warbler as its sole representative, however the South American Classification Committee of the AOU continue to place Kentucky warbler and mourning warbler with this genus.
|Wikimedia Commons has media related to Oporornis agilis.|
- BirdLife International (2012). "Oporornis agilis". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- "Connecticut Warbler, Life History, All About Birds – Cornell Lab of Ornithology". Allaboutbirds.org. Retrieved 2013-02-23.
- "Connecticut warbler videos, photos and facts – Oporornis agilis". ARKive. 2013-02-19. Retrieved 2013-02-23.
- Lawrence H. Walkinshaw and William A. Dyer (1961). "The Connecticut Warbler in Michigan". The Auk 78 (3): 379–388. doi:10.2307/4082276. JSTOR 4082276.
- CRC Handbook of Avian Body Masses, John B. Dunning Jr. (ed.). CRC Press (1992), ISBN 978-0-8493-4258-5.