Grace’s Warbler (Dendroica graciae)

Distribution

Breeding: Scattered populations in the mountains from southern Nevada, southern Utah, and southwestern Colorado, south through western and central Mexico to Nicaragua.

Winter: The highlands of western Mexico, south to Nicaragua.

Breeding habitat

Breeds almost exclusively in open forest of tall pines, generally from 6,550–9,850 feet (2,000–3,000 meters). Ponderosa pines are occupied in most of the U.S. range except along the Mexican border, where Apache and Chihuahua pines are also used. Breeding habitat may include a mixture of oaks, junipers, and firs, but pines are almost always an important element. At a few breeding sites near the edge of the species’ range, white firs rather than pines are occupied.

Conservation status

This species is of moderate conservation importance, because of its relatively small and patchy distribution, and its restriction to mature coniferous forests. Populations are not well monitored in any part of its range, and habitat requirements are poorly known.

Description

Male: One of the smallest Dendroica warblers, moderately long tail, fine bill. Gray above, black streaks on back and crown. Throat, upper breast yellow; remaining underparts white with dark streaks on sides. The yellow eyebrow turns white behind eye. Wings and tail are dark, with 2 white wing bars and white outer tail feathers.

Female: Similar to adult male, but upperparts are duller gray, black streaks on flanks are finer.

Juvenile: Resembles adults, except lacks yellow on throat and breast, underparts buffy white with breast lightly spotted and streaked.

Vocalizations

Songs: A slightly rising and accelerating series of chee notes, perhaps too slow to be considered a trill, lasting about 2 seconds. The song consists of two (occasionally three) slightly differing phrases, chew chew chew chew chew chew chee chee chee. Each male has several variations of this song, singing these song variants in different combinations in different contexts.

Calls: A soft slurred chip; the flight note is a very high, thin sip.

Foraging strategy

Most commonly forages in the very upper canopies of the tree, gleaning food from leaves and branches of pines, hemlocks, and spruces. Occasionally catches flying insects on the wing.

Diet

Poorly known, presumably largely or entirely insects.

Behavior and displays

• Because this small bird lives high up in pine trees and is difficult to observe, little is known of its life history.

• It moves from treetop to treetop with a quick erratic flight, darting out of the canopy to catch prey in midair.

Courtship

• No information.

Nesting

Nest Site: High limbs of pine trees, usually well out on a branch or in the crown. Often hidden from view, as nest is usually concealed in foliage or in the middle of bunches of pine needles.

Height: Usually high, ranging from 18–65 feet (6–20 meters).

Nest: A compact cup of hair, vegetable fibers, plant down, catkins, and bud-scales, wool, and caterpillar webs, often lined with feathers and hair. Probably built by female alone.

Eggs: 3–4 white to creamy eggs are marked with browns, usually wreathed.

Incubation period: No information.

Nestling period: Little information. Young are altricial, down grayish, mouth pink; tended by both parents.

Fledgling period: No information.

Broods: Double brooded.

Cowbird Parasitism: No information.