A medium-sized (4 ½ -5 ½ inches) wood warbler, the male Chestnut-sided Warbler is most easily identified by its pale breast, streaked back, yellow crown, and conspicuous chestnut flanks. Female Chestnut-sided Warblers are similar to males, but are somewhat duller, especially on the flanks. No other wood warbler breeding in North America possesses the combination of chestnut flanks and yellow crown characteristic of this species. The Chestnut-sided Warbler primarily breeds across southern Canada and the northeastern United States. Smaller numbers breed at higher elevations in the Appalachian Mountains as far south as northern Georgia. In winter, the Chestnut-sided Warbler may be found in southern Mexico and Central America. Chestnut-sided Warblers breed in a variety of semi-open deciduous forests, particularly in areas of shrubby growth created by forest fires and other types of ecological disturbance. In winter, this species may be found in and around humid tropical forests. Chestnut-sided Warblers primarily eat small invertebrates, including insects and spiders, although this species may eat some plant material, particularly fruits and berries, during the winter. In appropriate habitat, Chestnut-sided Warblers may be observed foraging for insects underneath leaves in shrubs and lower parts of the canopy. Birdwatchers may also listen for this species’ song, a whistled “please please pleased to meet’cha.” Chestnut-sided Warblers are primarily active during the day, but, like many migratory songbirds, this species migrates at night.
The chestnut-sided warbler (Setophaga pensylvanica) is a New World warbler. They breed in eastern North America and in southern Canada westwards to the Canadian Prairies. They also breed in the Great Lakes region and in the eastern United States.
The genus name Setophaga is from Ancient Greek ses, "moth", and phagos, "eating", and the specific pennsylvanicus means "Pennsylvania".[2]
These birds are migratory, wintering in Central America south to northern Colombia,[3] with a confirmed sighting[4] from as far south as Ecuador; they are also very rare vagrants to western Europe. They arrive in their breeding range in May and depart by mid-September.[5]
This species is a moderately-sized New World warbler. Despite having very different plumage, it is thought to be closely related to the widespread yellow warbler. In total, this species measures from 10 to 14 cm (3.9 to 5.5 in) in length and spans 16 to 21 cm (6.3 to 8.3 in) across the wings. Body weight ranges from 8 to 13.1 g (0.28 to 0.46 oz). Among standard measurements, the wing chord is 5.7 to 6.8 cm (2.2 to 2.7 in), the tail is 4.2 to 5.8 cm (1.7 to 2.3 in), the bill is 0.9 to 1 cm (0.35 to 0.39 in) and the tarsus is 1.7 to 1.9 cm (0.67 to 0.75 in).[6]
In the summer, male chestnut-sided warblers are unmistakable in appearance. They display dark-streaked gray backs, white faces, black eyestripes and yellow crowns. Their underparts are white, with chestnut flanks, and they also have two white wing bars. The adult females resemble washed-out versions of the summer male, and in particular, the females lack the strong head pattern, and also have little to no chestnut coloring on their flanks.
Non-breeding birds of both sexes have bright yellow-green crowns, white eye-rings on a grey face, and unstreaked underparts. They also have unstreaked pale grey breasts. Their wing bars are always present in their plumages. Their lack of streaking and yellowish backs help to distinguish this species from the larger blackpoll warbler in the fall.
The songs are high whistled lines often described as pleased, pleased, pleased to MEECHA. This accented song is used primarily to attract a female and decrease in frequency once nesting is well under way. Males also sing unaccented songs (without the MEECHA at the end) and these are used mostly in territory defense and aggressive encounters with other males. Some males sing only unaccented songs, and they are less successful at securing mates than males that sing both songs. Their calls are harsh chips. Despite the fact that songs for courtship do not vary across small distances, songs for aggression are highly localized, a possible explanation being that female Chestnut-Sided Warblers disperse over long distances.[7]
The chestnut-sided warbler has benefited from the clearing of mature forests. They make use of the abundant second growth habitats.[8] In the tropics where they winter however, the species occurs mostly in mature tropical rainforests. Their cup-shaped nests are placed in a low bush, which is usually located in young deciduous woodland or scrub. These birds lay 3–5 eggs that are creamy white or greenish with brown speckles in color. The nest is a small cup woven of bark strips, weed stems, grasses, and plant down. The nest is usually placed in a small crotch of a shrub or vertical tangle of vines no more than 2 m (6.6 ft) above the ground.[9] This species is frequently parasitized by brown-headed cowbirds.
This bird's numbers have increased as second growth forest became more common in the east in the late 19th century; their numbers have declined slightly since then.
Chestnut-sided warblers are primarily insectivorous. They forage actively in shrubs and small trees, and sometimes will attempt to catch insects in mid-air. Most foraging consists of gleaning insects from foliage. They will include berries in their winter diets, such as those of Cymbopetalum mayanum; such trees can be used to attract wintering birds into gardens and parks.[10]
Male, Ottawa, Ontario The chestnut-sided warbler (Setophaga pensylvanica) is a New World warbler. They breed in eastern North America and in southern Canada westwards to the Canadian Prairies. They also breed in the Great Lakes region and in the eastern United States.
