Microchera chionura (Gould, 1851)

Species Identification

The white-tailed emerald (Microchera chionura) measures 7.5 to 8 centimeters (3.0 to 3.1 inches) in total length.

Size and Weight

Males weigh approximately 3.3 grams (0.12 ounces), while females weigh 3.1 grams (0.11 ounces).

Bill Morphology

Both sexes share an almost straight black bill, with a pinkish base on the mandible.

Adult Male Upperparts

Adult males have bronzy green upperparts that darken to copper-bronze on the uppertail coverts.

Adult Male Tail Feathers

Their central two pairs of tail feathers are copper-bronze, and the outer three pairs are white with black tips.

Adult Male Underparts

Adult males have a glittering green throat and chest, with white belly, vent, and undertail coverts.

Adult Female Upperparts

Adult females also have bronzy green upperparts.

Adult Female Tail Feathers

Their central two pairs of tail feathers are bronzy, and the outer three pairs are white with a black band near the tip.

Adult Female Underparts

Female underparts are dull white, with bronzy green flanks.

Immature Male Plumage

Immature males resemble adult males but have duller underparts, with grayish buff feather fringes.

Immature Female Plumage

Immature females have grayer underparts than adult females.

Geographic Range

The white-tailed emerald occurs in the highlands of the Pacific slope, ranging from south-central Costa Rica to central Panama, and is also found locally on Panama's Caribbean slope.

Habitat Types

It inhabits the edges and interior of moist to humid montane forest and secondary forest, and also occurs in plantations and gardens.

Forest Interior Niche Partitioning

Within forest interiors, males are often found in the canopy while females occupy the understory.

Elevation Range

This species occurs at elevations between 750 and 2,000 meters (2,500 to 6,600 feet); in Costa Rica, it breeds mostly between 1,000 and 1,700 meters (3,300 to 5,600 feet).