Olive-sided flycatcher -- 绿胁绿霸鹟 (Contopus cooperi)

The olive-sided flycatcher (Contopus cooperi) is one of the most recognisable birds of North America’s coniferous forests, its distinctive calls often heard ringing from prominent perches in the tallest trees. Its characteristic song sounds like “quick, three beers” ⁽²⁾. 

The olive-sided flycatcher is a large and stocky flycatcher with a large head and a short tail. True to its name, this species is olive-grey along its sides and flanks. The upperparts are deep brownish olive-grey, and there is white on the throat, breast and belly. The wings are dark with indistinct, pale greyish wing bars, and there is a white tuft above the wing, along the side of the rump. Occasionally there is a white patch on the sides of the body. The upper mandible of the beak is blackish and the lower mandible is pale, with a dark tip ⁽²⁾.

Synonyms

Contopus borealis.

Size

Length: 18 - 20 cm ⁽²⁾

Weight

32 - 37 g ⁽²⁾

The olive-sided flycatcher is an impressive aerial acrobat. During courtship, pairs gracefully ‘dance’ together in a series of synchronized downward swoops. The female solicits copulation by sitting next to the male on a branch and by fluttering the half-open wings. Olive-sided flycatcher pairs are monogamous, and produce three to four eggs each nesting season. The nest is an open cup built on a horizontal branch of a coniferous tree, well out from the trunk. As in other members of the “tyrant” group of flycatchers (Tyrannidae), the olive-sided flycatcher pair aggressively defend a territory, which can sometimes extend for up to 40 to 45 hectares around the nest. The female olive-sided flycatcher incubates the eggs for 15 to 19 days, while the male brings food ⁽²⁾. 

The olive-sided flycatcher preys almost exclusively on flying insects, such as bees, wasps, grasshoppers and dragonflies. It catches its prey in the air by quickly swooping from a perch at the top of a tall tree ^{(2) (3)}.

The olive-sided flycatcher undergoes one of the longest migrations of all Nearctic migrants. It spends summer breeding across Canada and the north-eastern United States, from sea level up to elevations of 3,350 metres in the Rocky Mountains. In late summer, it migrates to its wintering grounds in Panama and the Andes Mountains of South America ⁽²⁾.

This widely distributed songbird breeds at the edges and in the openings of coniferous forests, as well as the forested edges of bogs, marshes and rivers ^{(2) (3)}. It prefers to nest in forest habitats with tall, prominent trees, but will also nest in burned or logged forests if snags are present that can act as foraging perches ⁽⁴⁾.

The olive-sided flycatcher is classified as Near Threatened (NT) on the IUCN Red List ⁽¹⁾.

Declines in the olive-sided flycatcher population have been observed across this species’ range, with the loss and degradation of forest habitat in South America the most likely cause. However, this decline has been mirrored by population crashes of other aerial insectivores, suggesting that declines in insect prey, possibly due to pesticide use and climate change, may also be threatening the olive-sided flycatcher ⁽²⁾.

The olive-sided flycatcher has been listed as a ‘Species of Concern’ or as ‘Threatened’ in the U.S. and Canada ⁽²⁾. Currently, there are no specific conservation actions known for this species, but proposed conservation measures include identifying the causes of its decline and developing and implementing relevant actions ⁽⁴⁾.

Find out more about the olive-sided flycatcher:

• BirdLife International - Olive-sided flycatcher:
  http://www.birdlife.org/datazone/speciesfactsheet.php?id=4264
• Birds of North America Online - Olive-sided flycatcher:
  http://bna.birds.cornell.edu/bna/species/502/

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
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Incubate

To keep eggs warm so that development is possible.

Insectivore

An organism that feeds mainly on insects.

Mandible

In birds, the lower jaw and beak, but the term is also used to denote the two parts of the beak.

Monogamous

Having only one mate during a breeding season, or throughout the breeding life of a pair.

Nearctic

The region including North America south to Mexico.

Territory

An area occupied and defended by an animal, a pair of animals or a group.

1. IUCN Red List (August, 2011)
   http://www.iucnredlist.org/
2. Altman, B. and Sallabanks, R. (2000) Olive-sided flycatcher (Contopus cooperi). In: Poole, A. (Ed.) Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
   http://bna.birds.cornell.edu/bna/species/502/
3. Cornell Lab of Ornithology: All About Birds - Olive-sided flycatcher, Contopus cooperi (August, 2011)
   http://www.birds.cornell.edu/bfl/speciesaccts/olsfly.html
4. BirdLife International (August, 2011)
   http://www.birdlife.org/datazone/speciesfactsheet.php?id=4264