The Connecticut warbler (Oporornis agilis) is a small songbird of the New World warbler family.
Description
These medium-sized warblers measure in length, with a wingspan. Connecticut warblers weigh when they fledge, attaining an average weight of around as adults. However, birds preparing for migration pack on more weight to survive the strenuous journey and can weigh up to . This species has light yellow underparts and olive upperparts; they have a light eye-ring, pink legs, a long tail, and a thin pointed bill. Males have a grey hood; females and immatures are more brown and have a whitish throat.
200px|thumb|Male (atop) and female Connecticut warbler. Note how dull the female is in contrast to the male.
They forage on the ground, picking among dead leaves, or hop along branches. Like most warblers, these birds mainly eat insects and similar small invertebrates. They will also 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.
Despite its name, this bird only rarely visits Connecticut during migration. It was named by Alexander Wilson who observed the first classified specimen. They are fairly elusive birds, but it appears that their numbers may be declining due to loss of winter habitat.
Taxonomy
The Connecticut warbler is now the only member of the genus Oporornis. The mourning, Kentucky, and MacGillivray's warblers were formerly included in Oporornis, but recent studies have found that these three warblers are more closely related to the yellowthroats in the genus Geothlypis.
Habitat
Their breeding habitat is bogs or open deciduous woods near water, especially with poplar, spruce, tamarack or aspen, in central Canada and states bordering the Great Lakes. These habitats tend to be in rather remote areas that are hard to access for fieldwork; therefore, there is little data available on this species of birds.
Breeding
Courtship begins right after the migrants arrive on their breeding grounds. It correlates with the time when males start to sing as this is how they court females. Couples have one brood per season. Connecticut warblers like to nest in thick understory where their young are protected from predators. Most lay in mid-June, though some populations have been observed to lay in July. Their eggs have a creamy color and they are speckled and blotched with chestnut and bay. Only females incubate. Fledglings are observed in late July and at the latest at the end of August. Both parents feed their young caterpillars, larvae, moths, and berries. The call is a nasal pitch, it sounds like a raspy "witch". Like many songbirds, its song is heard during the breeding season but rarely during the fall. Males are highly territorial during breeding season, they defend an area which ranges from 0.24–0.48 hectares. These birds migrate to the Amazon Basin in South America in winter. Specimens have been observed in Colombia (north & southeast), Venezuela (northeast & interior), Guyana (at the border), and Peru (South). In Alberta breeding sites, noise disturbances from gas pipelines are detrimental to the species as well. Studies show that Connecticut warblers did well in forests that have been cleared of shrubs and understory as they prefer trees; however, their abundance decreased in areas where the forest was clear-cut. Nevertheless, some of its populations in Saskatchewan, Michigan, Minnesota, and Wisconsin are at risk. Conservation efforts are difficult due to a lack of research, though a handful of researchers have written some management plans, focusing on the preservation of woody wetlands, which are the Connecticut warbler's favored habitat.