The olive-sided flycatcher (Contopus cooperi) is a small to medium sized passerine bird in the family Tyrannidae, the tyrant flycatcher family. It is a migratory species that travels from South America to North America to breed during the summer. It is an agile flyer and mainly consumes flying insects caught in flight. Since 2016, this species has been assessed as being near-threatened globally (IUCN) and threatened in Canada (SRA) due to its declining populations.
Description
Identification
The olive-sided flycatcher is a small to medium-sized passerine, smaller than an American robin, but bigger than sparrows. It can be identified by its olive-grey or grey-brownish plumage above with a white mid-breast section and throat. The olive tones on its back and wings are seen mainly in optimal light and when the feathers are freshly moulted. The sides of the breast area are grey and make the bird look like it is wearing a vest. It has a relatively long bill and long wings for its size. Sometimes, some of its head feathers can be raised, which make it look like it has a small crest. Male and female look similar. Olive-sided flycatchers perch in upright positions on top of dead branches or trees.
{| class="wikitable"
|+Measurements
The species has often been considered to be monotypic; the Clements Checklist and AOS Checklist of North American Birds currently do not recognize any subspecies. However, the disjunct populations that breeds in southern California and Baja California is sometimes recognized as a distinct subspecies, C. cooperi majorinus. This subspecies is a short-distance migrant and has longer wings and tail feathers than birds from elsewhere.
Distribution and habitat
The olive-sided flycatcher is distributed throughout North and South America. Its breeding habitat ranges from California and New Mexico all the way up to central Alaska, then across Canada (except for most of the Northwest Territories and Nunavut) and through a portion of northeastern US. Its non-breeding habitat is mainly in the northern part of South America and a small area in Central America.
Their breeding habitat is mainly in open areas or edges of boreal, coniferous forests or temperate western forests, in areas up to 10,000 feet in elevation (e.g., in the Rockies), and always near water. They can also nest in cities or on farms. In their non-breeding habitat, olive-sided flycatchers use similar habitats as their breeding habitats, such as open areas and forest edges, but do not need water proximity as much as in their breeding habitat. They are also associated with habitats with very tall trees. Two forest habitats used by olive-sided flycatchers in the winter are tropical montane and tropical lowland evergreen forests.
Behaviour
Vocalizations
During the breeding, olive-sided flycatcher males sing a song to attract a mate. The mnemonic for its song is "Quick, three beers!" with three successive higher-pitched sounds. The first sound is shorter and not as high-pitched and loud as the two others. Sometimes, during mating season, males can produce growling sounds or squeaks when in conflict with other males. This species' most frequent call is three quick successive pip sounds.
The rate at which males sing varies throughout the breeding season. This variation appears to be correlated indirectly with the breeding status (single, paired, or feeding young) of the individuals.
Reproduction
Olive-sided flycatchers breed once per year and usually lay clutches of 3 to 4 eggs. The incubation period lasts for 15 to 19 days and so does the nestling stage. The egg is approximately 0.8–0.9 inches long by 0.6–0.7 inches wide and is a creamy white colour with brownish spots that form a ring on the larger end of the egg. The nest location is chosen by the female and is usually on a horizontal branch of coniferous trees, but they have also been seen on other types of trees. The lowest nest was 5 feet high and the highest was 197 feet. In Western regions, olive-sided flycatchers tend to have higher nests than in their Eastern distributions. The nest is about 4.6 inches wide on the outside and 2.8 inches wide on the inside and is cup-shaped. The outer part is made with twigs and small branches, while the inside is usually lined with finer material such as grass, lichen, and needles. The hatching are born naked and helpless.
Migration
Of all the flycatcher species that breed in the United States, the olive-sided flycatcher has the longest migration. Some olive-sided flycatchers migrate up to 7,000 miles traveling between central Alaska and Bolivia.
Status and conservation
According to the IUCN Red List in 2016, the olive-sided flycatcher is classified as a Near Threatened species. The Canadian Species at Risk Act lists the olive-sided flycatcher as threatened due to its declining population.
The olive-sided flycatcher's global population is estimated at 1.9 million individuals but appears to be declining at a rate of 3% of the population per year
Threats
Research in Eastern Canada showed that disturbances caused by human activities and road proximity have a negative impact on olive-sided flycatcher populations in Canadian national parks. This study helped quantify the importance of protected areas for the species.
The loss of wintering habitat might be one of the main causes for its population decline.