Palmchats (Dulidae)

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Palmchats

(Dulidae)

Class Aves

Order Passeriformes

Suborder Passeri (Oscines)

Family Dulidae

Thumbnail description
A highly vocal bird that flocks in small bands, generally around royal palm trees; brown above and have yellowish white underparts with heavy brown streaking

Size
7.5–8 in (19–20 cm)

Number of genera, species
1 genus; 1 species

Habitat
Distributed throughout the low to mid-elevations, especially in royal palm savannas

Conservation status
Not threatened

Distribution
Endemic to Hispaniola (Dominican Republic and Haiti), including Gonave and the Saona Islands

Evolution and systematics

The palmchat (Dulus dominicus) is the only member of its genus and family. Todies and palmchats are the only two endemic bird families of the Caribbean. Because of the palmchat's evolutionary and taxonomic importance, the Dominican Republic (which occupies two thirds of the island of Hispaniola) has declared it the national bird.

The palmchat was first described in 1766 by Linnaeus as a member of the genus Tanagra. In 1847 Haurtlaub classified it under its present genus, Dulus.

Surprisingly, palmchats are unrelated to any other Hispaniolan bird species, but are distantly related to North American waxwings (Bombycillidae), with whom they share similar skeletal structures.

Physical characteristics

The palmchat is 7.5–8 in (19–20 cm) long with a moderately long tail and strong bill. The bird is olive brown above with a yellowish green wash on the rump and edges of the primary wing feathers. The underside is yellowish white with sooty brown streaking. Its bill is yellow, its iris brownish red. The sexes have similar plumage; immature birds have darker throats and forenecks.

Distribution

The palmchat is endemic to the island of Hispaniola, including Gonave and the Saona Islands.

Habitat

Palmchat are common and widely distributed throughout the low to mid elevations, although occasionally they extend into altitudes of 4,900 ft (1,500 m) or more. They are absent from the tallest peaks and mountains, and from dense rain-forests; they prefer royal palm savannas and valleys.

Behavior

Palmchats are gregarious and live in small bands, which have a communal nest as the center of activity. Groups consist of several pairs that tend to be sociable and affectionate; they continuously sidle up to and perch beside their companions.

When they are not searching for food, the birds rest on palm fronds or perch on the projected spikes above palm trees. They often use their nests as resting spots, and as common roosts at night. In the morning, groups of up to eight individuals can be seen perched on limbs to preen and dry themselves in the sun.

Palmchats often seem alert and vivacious because they stand with bodies erect and tails pointing straight down. They are very vocal and noisy, especially around their nests. They utter a wide array of call notes, but nothing that can be considered a song.

Feeding ecology and diet

Palmchats are fruit eaters. They prefer a variety of berries, including those from palm trees. Undoubtedly they help

disperse the seeds of royal palms, gumbo-limbo trees, and many other fruiting tree species. Their diet includes flower buds and blossoms, especially orchid tree blooms, but the birds are not considered harmful to plants or trees.

Palmchats feed by searching through trees in twos or threes. Insects provide an alternate source of dietary protein, and at times the birds hunt insects by pursuing them in flight.

Reproductive biology

The nest is a large structure of twigs built around the crown of a palm and supported by lower fronds. Twigs are interlaced loosely to form a disorderly looking nest that measures 3–6.5 ft (1–2 m) in diameter. Twigs chosen for their nests are large (10–18 in [25–45 cm]), so it is impressive to see these relatively small birds struggling along with large twigs in their bills.

The nest is built by several pairs of birds that have individual nest chambers with separate entrances. The inner chamber is lined with shredded bark, on which eggs are laid. The female lays two to four purplish gray eggs that are heavily spotted at the broad end. Breeding is mainly between March and June but has been recorded throughout the year.

Old nests tend to fall to the ground as supporting palm fronds mature and break. Immediately afterward, if the nest is still active, twigs from the fallen nest are usually reused. In certain habitats in Haiti and the Dominican Republic, where palms are uncommon (particularly in dry scrub and pine forests), palmchats are reported to build nests on telephone poles and in pine trees, and sometimes in mature broadleaf trees.

Palmchats are parasitized by a fly of the Philornis genus, whose eggs are generally laid on nestling birds and develop in a sac under the skin on the head or under the wing. The parasites apparently do no harm and when they complete the larval cycle abandon their hosts without complications. Up to 90% of all birds examined were hosts to the fly larvae.

Conservation status

Not threatened.

Significance to humans

None known.

Resources

Books

Dod, A.S. Aves de La Republica Dominicana. Santo Domingo: Museo Nacional de Historia Natural, 1978.

Raffaele, Herbert, James Wiley, Orlando Garrido, Allan Keith, and Janis Raffaele. A Guide to the Birds of the West Indies. Princeton: Princeton University Press, 1998.

Wetmore, A., and B.H. Swales. The Birds of Haiti and The Dominican Republic. U.S. National Museum, Bulletin 155. Washington, DC: Smithsonian Institution, 1931.