Green Jay

Cyanocorax yncas

  • Version: 2.0 — Published January 1, 1995
  • Douglas C. Gayou

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Figure 1. Distribution of the Green Jay in North and Middle America.

See text for range of South American population.

Adult Green Jay; Texas, March.

Adult Green Jay of the northern subspecies C. y. glaucescense. Hidalgo County, Texas. March., Mar 25, 2006; photographer Gerrit Vyn

The Green Jay, a tropical member of North America's avifauna, occurs as two disjunct, resident populations: one from just north of the Rio Grande River in s. Texas to n.-central Honduras and a second from Colombia and Venezuela south through eastern Ecuador and Peru to Bolivia. In south Texas, where this species has been most thoroughly studied, it occupies permanent all-purpose territories in a variety of scrub and forest habitats, breeding from April to June.

The south Texas population of Green Jay is unusual in retaining related nonbreeders in family flocks, but without cooperative breeding (i.e., helpers-at-the-nest). Flocks in this region consist of a breeding pair, current year's nestlings, and one year-old non-breeding jays from the previous year's reproductive effort. The one year olds provide a significant amount of territorial defense, which aids parents, but they are ejected from the family flock soon after the current year's nestlings have fledged. In the Colombian population, by contrast, this species breeds cooperatively with helpers-at-the-nest, a difference apparently related to food resources being less abundant and more unevenly distributed there.

This species has a variety of calls, as befits a flocking, social corvid. During the non-breeding season, flocks are often noisy and conspicuous; during the breeding season, they are much quieter. Arthropods, vertebrates, seeds, and fruit make up the bulk of this species' diet.

The Green Jay remains relatively unstudied. Previous research has been restricted to one detailed study of the Colombian population's social system (Alvarez 1975), and to the breeding of a Mexican pair in captivity (Roles 1971). The southern Texas population has been the subject of one long-term study (Gayou Gayou 1982, Gayou 1984, Gayou 1985, Gayou 1986). Fundamental life history data are still lacking.

Recommended Citation

Gayou, D. C. (1995). Green Jay (Cyanocorax yncas), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.