Unicolored jay


The unicolored jay is a species of bird in the family Corvidae, the crows and jays. It is found in El Salvador, Guatemala, Honduras, and Mexico.

Taxonomy and systematics

The unicolored jay was originally described in 1847 as Cyanocorax unicolor. Its current genus Aphelocoma is from Latinized Ancient Greek apheles- "simple" + Latin coma "hair", in reference to the lack of striped or banded feathers in this genus, compared to other jays. It is apparently a basal member of the genus.
The unicolored jay has these five subspecies:A. u. guerrerensis Nelson, 1903A. u. concolor A. u. oaxacae Pitelka, 1946A. u. unicolor A. u. griscomi Van Rossem, 1928
Some of the subspecies were originally described as full species. The five exhibit much genetic variation and have long been isolated from each other. In 2020 the American Ornithological Society declined to reclassify them into four species.

Description

The unicolored jay is about long. The nominate subspecies A. u. unicolor weighs about. The sexes have the same plumage. The nominate subspecies is entirely deep blue to purplish blue that is somewhat darker on the sides of the head and the throat. Juveniles are a slightly bluish gray that is duller than adult plumage. Subspecies A. u. griscomi has the same plumage as the nominate. A. u. guerrerensis is the most purplish subspecies, A. u. concolor is a paler blue than the nominate, and A. u. oaxacae is somewhat darker than the nominate. Adults of all subspecies have a dark brown iris, a black bill, and black legs and feet. Immatures have pale bills.

Distribution and habitat

The unicolored jay has a highly disjunct distribution. The subspecies are found thus:A. u. guerrerensis southwestern Mexico in the Sierra Madre del Sur of west-central GuerreroA. u. concolor: eastern Mexican states of eastern Hidalgo, west-central Veracruz, México, and PueblaA. u. oaxacae: southern Mexico in OaxacaA. u. unicolor: Mexico's Chiapas state and Guatemala's Sierra de las MinasA. u. griscomi: northern El Salvador, western and central Honduras, and incidentally in extreme north-central Nicaragua
The unicolored jay is a bird of the subtropical and lower temperate zones. In Chiapas it primarily inhabits pine-oak forest with a somewhat open canopy. Elsewhere it is found in pine-oak, cloudforest, and pine savanna. Sources differ on the species' overall elevational range with both and being stated. Outside of Mexico it ranges from.

Behavior

Movement

The unicolored jay is a year-round resident.

Feeding

The unicolored jay is omnivorous. Most of the diet data come from Montebello, Chiapas, where it was observed feeding on various fruits, many types of larval and adult insects, discarded human food, and once a hummingbird nestling. There the species foraged in vegetation and only rarely on the ground, searching bromeliads, foliage, and branches and sometimes hanging upside down.

Breeding

Most data on the unicolored jay's breeding biology is from Montebello. The species is a cooperative breeder with groups of up to nine birds formed by one primary pair, non- or seldom-breeding males, non-breeding females, and the main pair's offspring. The breeding season spans from mid-January at least to April. The nest has a foundation of sticks lined with Usnea lichen and sometimes some pine needles. Usually the primary pair built the nest but sometimes other group members contributed. Nests were found between about above the ground and mostly in oak trees. The only described clutch was of three unmarked pale blue eggs. The group's primary female alone incubated the clutch; the incubation period is not known. Fledging occurred 21 to 26 days after hatch. Many members of the group provisioned the brooding female and nestlings.

Vocalization

Though recordings of unicolored jay vocalizations come from most of its range, detailed analyses come primarily from the Montebello studies. The birds there made hundreds of variants of their calls though many were only subtly different from each other. The calls were described as grating/harsh, musical/resonant, whistled, loud, and soft. Some have been written as weet, zhreenk, ralph, gronk, cleemp, dzee-oo, poit, kuk, and wah.

Status

The IUCN has assessed the unicolored jay as being of Least Concern. It has a very large range; its estimated population of at least 50,000 mature individuals is believed to be decreasing. No immediate threats have been identified. It is considered "rare to uncommon and local" in northern Central America.