Connecticut warbler (Oporornis agilis)

Description

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Connecticut warbler fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Connecticut warbler description

The Connecticut warbler (Oporornis agilis) is one of the most poorly known songbirds in North America ^{(2) (4)}. This shy, retiring warbler remains largely unstudied, in part because of its secretive behaviour, and its nest was not discovered until nearly 70 years after the species was first described ⁽²⁾.

The Connecticut warbler is predominately olive to olive-brown above, with pale yellow underparts and a grey or brownish hood, which extends onto the lower throat ^{(2) (3)}. The male and female Connecticut warbler are similar in appearance throughout the year, but the female is generally duller than the male. Immature Connecticut warblers are duller than the adults, with browner heads and paler throats. In all plumages there is a complete white ring around each eye. The Connecticut warbler has a short tail, and its legs and toes are pink ^{(2) (3)}.

This species is unique among warblers in its habit of walking along the ground in a bouncy manner, with its short tail bobbing up and down ⁽³⁾.

Synonyms

Geothlypis agilis.

Size

Length: 13 - 15 cm ⁽²⁾

Wingspan: 23 cm ⁽³⁾

Weight

c. 15 g ⁽²⁾

Connecticut warbler biology

Much of what is known about the Connecticut warbler comes from observations of a single nesting pair in Michigan, and there are no rigorous, experimental studies of its general biology ⁽²⁾. The male Connecticut warbler produces a loud, ringing song in which a two- or three-part phrase is repeated several times in a row ⁽²⁾. It has been described as sounding like “tweet chuh WHIP-uh chee-uh-WHIP-uh chee-uh-WAY” ⁽³⁾. The male usually sings from elevated tree branches in the low to middle canopy, with the greatest activity early in the morning ⁽⁴⁾. The song is presumably used to advertise territorial ownership and attract females ⁽²⁾.

This species is highly territorial during the summer months, when courtship, mating and nesting occur ⁽²⁾. The Connecticut warbler probably breeds from mid-June to early August ⁽⁴⁾. Its nest is a concealed, compact cup of grass and leaves, lined with soft material and located on or near the ground ^{(3) (4)}. The female Connecticut warbler lays a single clutch of three to five eggs in each nesting season. The eggs are oval, creamy-white and speckled with drab brown spots and blotches ⁽⁶⁾.

There is little other information available on the biology of the Connecticut warbler, but it is thought to live to at least four years of age ⁽⁶⁾.

Connecticut warbler range

The Connecticut warbler arrives at its breeding grounds in May, when it ranges from central British Columbia, east across central Canada, to eastern Quebec and the northern Great Lakes region of the United States ^{(2) (4)}. In August, this species migrates to its wintering range east of the Andes around the Amazon basin in Colombia, Venezuela, Peru, French Guiana, and Brazil ⁽²⁾.

Although the first specimen of this species was collected in Connecticut, the common name of the Connecticut warbler is misleading, as it does not breed in this state and is not a common migrant there ⁽²⁾.

Connecticut warbler habitat

The Connecticut warbler breeds in open woods, forests and boggy areas at lower elevations ^{(2) (3)}. It prefers mature, multi-layered pine stands, particularly those with a dense hardwood understory ^{(4) (5)}.

The wintering range of the Connecticut warbler is characterized by woodland, forest edges, and dense, shrubby second-growth ⁽²⁾.

Connecticut warbler status

The Connecticut warbler is classified as Least Concern (LC) on the IUCN Red List ⁽¹⁾.

Connecticut warbler threats

Although the Connecticut warbler is not currently considered globally threatened ⁽⁷⁾, its population underwent a decline between the late 1800s and early 1900s, which was attributed to over-collecting ⁽²⁾. During its annual autumn migration, many fatalities occur due to collisions with lighthouses and other buildings ⁽²⁾.

The Connecticut warbler may also be vulnerable to habitat loss in its wintering grounds in South America ⁽²⁾. Other threats include loss of jack pine forest habitat and forest fragmentation in its breeding grounds ⁽⁶⁾.

Connecticut warbler conservation

The Connecticut warbler’s distribution is naturally patchy, even in suitable environments ⁽⁶⁾. However, it is not listed as ‘Endangered’ or ‘Threatened’ in any of the states in which it occurs ⁽²⁾.

There are no current conservation activities for the Connecticut warbler in the Michigan, Minnesota and Wisconsin National Forests, but draft guidelines have been written for the conservation of this species in the Chequamegon-Nicolet National Forest in Wisconsin. These include maintaining habitats with jack pine forest, mossy cover, and dense shrubbery, as these appear to be key aspects of this species’ habitat ⁽⁶⁾.

This shy warbler remains one of the most poorly known species in North America, and would therefore benefit from further studies into its biology, particularly its breeding behaviour. The distribution of the Connecticut warbler on its wintering grounds also needs to be documented ⁽²⁾.

Find out more

Find out more about the Connecticut warbler and its conservation:

• BirdLife International - Connecticut warbler:
  http://www.birdlife.org/datazone/speciesfactsheet.php?id=9134
• Birds of North America Online - Connecticut warbler (Oporornis agilis):
  http://bna.birds.cornell.edu/bna/species/320/

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Glossary

Second-growth

Vegetation that has re-grown after a major disturbance, such as fire or clearance.

Territorial

Describes an animal, a pair of animals or a colony that occupies and defends an area.

References

1. IUCN Red List (March, 2011)
   http://www.iucnredlist.org/
2. Pitocchelli, J., Bouchie, J. and Jones, D. (1997) Connecticut warbler (Oporornis agilis). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
   http://bna.birds.cornell.edu/bna/species/320/
3. Vuilleumier, F. (Ed.) (2009) American Museum of Natural History. Birds of North America: Western Region. DK Publishing, New York.
4. Campbell, R.W. (2001) The Birds of British Columbia. Volume 4: Passerines. Wood-warblers through Old World Sparrows. UBC Press, Vancouver, British Columbia.
5. Wisconsin Department of Natural Resources - Connecticut warbler (Oporornis agilis) (March, 2011)
   http://dnr.wi.gov/org/land/er/biodiversity/index.asp?mode=info&grp=7&speccode=abpbx11020
6. Kudell-Ekstrum, J. (2002) Conservation Assessment for the Connecticut Warbler (Oporornis agilis). USDA Forest Service, Eastern Region, Milwaukee, Wisconsin. Available at
   http://www.fs.fed.us/r9/wildlife/tes/ca-overview/docs/Connecticut-Warbler-CA.pdf
7. BirdLife International (August, 2011)
   http://www.birdlife.org/datazone/speciesfactsheet.php?id=9134