White-crested elaenia

The International Ornithological Committee (IOC) recognizes these five subspecies of the white-crested elaenia:^[2]

• E. a. griseigularis Sclater, PL, 1859
• E. a. diversa Zimmer, JT, 1941
• E. a. urubambae Zimmer, JT, 1941
• E. a. albiceps (D'Orbigny & Lafresnaye, 1837)
• E. a. modesta Tschudi, 1844

The South American Classification Committee of the American Ornithological Society (SACC), the Clements taxonomy, and BirdLife International's Handbook of the Birds of the World (HBW) recognize a sixth subspecies, E. a. chilensis (Hellmayr, 1927), that the IOC treats as the Chilean elaenia. The SACC is seeking a proposal to recognize it as a species.^{[2][3][4][5][excessive citations]}

Subspecies E. a. modesta was originally described as a species and was later reclassified as a subspecies of the white-crested elaenia. Significant evidence now suggests that it should again be treated as a full species.^[3][6]

This article follows the five-subspecies model.

The white-crested elaenia is 13.5 to 15 cm (5.3 to 5.9 in) long and weighs 12.5 to 24.2 g (0.44 to 0.85 oz). It is a small to medium size elaenia with a small bushy crest. The sexes have the same plumage. Adults of the nominate subspecies E. a. albiceps have a mostly dull olive to olive-gray head with a partially hidden white or creamy white stripe in the middle of the crest. They have whitish lores and eyering. Their upperparts are dull olive to olive-gray. Their wings are dusky with white or whitish tips on the coverts that show as two wing bars. Their flight feathers have narrow whitish or yellowish edges with dusky bases on the inner pairs. Their tail is dusky with narrow olive edges to the feathers. Their throat is light gray or whitish gray, their breast light gray or grayish brown, and their belly and undertail coverts whitish.^[6][7]

The other subspecies of the white-crested elaenia differ from the nominate and each other thus:^{[6][7][8][9][10][excessive citations]}

• E. a. griseigularis: paler upperparts than nominate, with less white on a shorter crest and a less distinct eyering
• E. a. diversa: like griseigularis with a whiter throat, less distinct wing bars, and more contrast between the flanks and belly
• E. a. urubambae: paler upperparts than nominate with paler lores, less prominent eyering, duller wing bars, and a pale yellow wash on the belly
• E. a. modesta: duller overall than nominate, with no distinct lores and eyering contrast, less distinct wing bars, and pale edges on the inner flight feathers extending through what is dusky on the nominate

Both sexes of all subspecies have a dark brown iris, a black or dark gray bill with a pale base to the mandible, and black or dark gray legs and feet.^[6]

The subspecies of the white-crested elaenia are found thus:^{[6][7][8][9][10][excessive citations]}

• E. a. griseigularis: from Nariño Department in far southwestern Colombia south through central Ecuador into northwestern Peru's Cajamarca Department
• E. a. diversa:north-central Peru from Cajamarca south to Huánuco Department
• E. a. urubambae: southeastern Peru's Urubamba River valley in Cuzco Department
• E. a. albiceps: from Puno Department in far southeastern Peru into Bolivia as far as Cochabamba Department
• E. a. modesta: breeds west of the Andes from Lambayeque Department in northwestern Peru south to Tarapacá Region in northern Chile and winters east of the Andes in Peru between San Martín Department and Madre de Dios Department

Elaenias listed as white-crested by the SACC have been recorded as vagrants on the Falkland Islands but without subspecies identification, so they could have been what the IOC but not the SACC recognizes as the Chilean elaenia. The Chilean elaenia is highly migratory.^[6][11]

Note that the range map uses HBW taxonomy and so includes the extensive range of the Chilean elaenia, which reaches far east of the white-crested elaenia's range.

The white-crested elaenia's habitat has been studied for all subspecies except E. a. modesta, and it is assumed to have similar requirements to the others. They inhabit the edges of subtropical and temperate forest, the interior of more open woodlands and secondary forest, and scrublands. In many areas the species favors intermontane valleys that are drier than the slopes above. In elevation it ranges up to 3,200 m (10,500 ft) in Colombia, between 1,500 and 2,800 m (4,900 and 9,200 ft) in Ecuador, and between 800 and 3,500 m (2,600 and 11,500 ft) on the west slope and 1,000 and 3,300 m (3,300 and 10,800 ft) on the east slope in Peru.^{[6][7][8][9][10][excessive citations]}

Subspecies E. a. modesta breeds west of the Andean crest and moves to the east side of the range for the austral winter. Flocks of up to 100 have been reported during migration, but as is the case with vagrants to the Falklands they could have been the highly migratory Chilean elaenias. The other subspecies are year-round residents.^[6][7]

The white-crested elaenia's diet has not been detailed but is known to include insects and fruit. It typically forages singly. It sometimes joins mixed-species feeding flocks, and often feeds at fruiting trees with individuals of its own and other species. It captures prey and plucks fruit by gleaning while perched and while briefly hovering.^[6][8]

Subspecies E. a. modesta apparently mostly breeds between December and February; the breeding seasons of the other subspecies are not known. Nothing else is known about the species' breeding biology.^[6]

The oldest known white-crested elaenia from banding studies was eight years and two months old, though it is uncertain whether this represents the maximum potential longevity of the species.^[12]

The white-crested elaenia's vocalizations apparently differ somewhat among the subspecies, though not all have been studied in detail. The dawn song of E. a. griseigularis is "a series of deep, burry, falling-rising djeewee notes interspersed with occasional per'brr'djwee notes" and its calls are "a low, rich, modulated djur and a longer, descending djeeer". The dawn song of E. a. albiceps is "a series of burry rising-falling-rising djww'awee notes interspersed with an occasional purt trr'cheewee". Its call are "a burry, sneezing whi'bur and a descending, burry wheer". The song of E. a. modesta has not been described; its call is "a pure, descending peeur".^[7]

The IUCN follows HBW taxonomy and so has included the Chilean elaenia in its assessment of the white-crested. The species together are assessed as being of Least Concern, with an unknown population size that is believed to be stable. No immediate threats have been identified.^[1] "A species that occupies forest edge and second-growth, it is likely that this species is relatively tolerant of habitat disturbance."^[6]

• White-crested Elaenia photo gallery VIREO
• Photo-Medium Res; Article & Synopsis avesdechile