The Chestnut-sided Warbler (Dendroica pensylvanica) is a New World warbler

New World warbler

The New World warblers or wood-warblers are a group of small, often colorful, passerine birds restricted to the New World. They are not related to the Old World warblers or the Australian warblers....

. They breed in eastern North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 and in southern Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 westwards to the Canadian Prairies

Canadian Prairies

The Canadian Prairies is a region of Canada, specifically in western Canada, which may correspond to several different definitions, natural or political. Notably, the Prairie provinces or simply the Prairies comprise the provinces of Alberta, Saskatchewan, and Manitoba, as they are largely covered...

. They also breed in the Great Lakes region and in the eastern USA.

Migration Range

These birds are migratory

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

, wintering in Central America

Central America

Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 south to northern Colombia

Colombia

Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

, with an unconfirmed sighting from as far south as Ecuador

Ecuador

Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

; they are also very rare vagrant

Vagrancy (biology)

Vagrancy is a phenomenon in biology whereby individual animals appear well outside their normal range; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used...

s to western Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

. They arrive in their breeding range in May and depart by mid-September.

Description

In the summer, male Chestnut-sided Warblers are unmistakable in appearance. They display dark-streaked gray backs, white faces, black eyestripes and greenish 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 less chestnut coloring on their flanks.

Non-breeding birds of both sexes have greenish heads, and greenish upperparts which are usually unstreaked. They also have unstreaked pale grey breasts. Their wing bars are always present in their plumages. Their lack of streaking helps to distinguish this species from the Blackpoll Warbler

Blackpoll Warbler

The Blackpoll Warbler, Dendroica striata , is a New World warbler. Breeding males are mostly black and white. They have a prominent black cap, white cheeks and white wing bars. The Blackpoll breeds in northern North America, from Alaska, through most of Canada, and into the Great Lakes region and...

 outside the breeding season.

Sound

The songs are whistled pleased, pleased, pleased to meecha lines. Their calls are harsh chips.

Breeding and Habitat

The Chestnut-sided Warbler has benefited from the clearing of mature forests. They make use of the abundant second growth habitats. 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. Their species is frequently parasitized by cowbirds

Brown-headed Cowbird

The Brown-headed Cowbird is a small brood parasitic icterid of temperate to subtropical North America. They are permanent residents in the southern parts of their range; northern birds migrate to the southern United States and Mexico in winter, returning to their summer habitat around March or...

.

Population

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.

Food

Chestnut-sided Warblers are insectivorous, but will include berries in their winter diets. They forage actively in shrubs and small trees, and sometimes will attempt to catch insects in mid-air.

External links

• Chestnut-sided Warbler videos, photos & sounds on the Internet Bird Collection
• Chestnut-sided Warbler - Dendroica Pensylvanica - USGS Patuxent Bird Identification InfoCenter
• Chestnut-sided Warbler Species Account - Cornell Lab of Ornithology
• Chestnut-sided Warbler Information and Photos - South Dakota Birds and Birding
• Chestnut-sided Warbler photo gallery VIREO
• Chestnut-sided Warbler at Animal Diversity Web