A colorful, pigeon-sized bird with temperate habitat preferences, the Thick-billed Parrot is a highly social species closely tied to conifer forests, in accord with its strong dietary emphasis on pine seeds. Thick-billed Parrots are almost always found in flocks, even during the breeding season, and their loud calls, which sound much like human laughter, can be heard from more than 1.5 km away under favorable conditions. In their daily movements, Thick-bills sometimes forage up to 15-25 km from nests and roosts, and their seasonal migrations sometimes extend hundreds of kilometers. Their long, pointed wings give them an almost falconlike silhouette, and they are capable of flight and maneuvers rapid enough to commonly elude pursuing Peregrine Falcons (Falco peregrinus) and Northern Goshawks (Accipiter gentilis). In extended flights, Thick-bills often adopt V-formations, much like those of waterfowl.
The Thick-billed Parrot and the extinct Carolina Parakeet (Conuropsis carolinensis) are the only parrot species whose natural distributions once included parts of the continental United States. The stronghold for the Carolina Parakeet was the southeastern states, although records for this species once extended as far west as Colorado (Mckinley 1964). The stronghold for the Thick-billed Parrot is the Sierra Madre Occidental of Mexico, but until the mid-twentieth century the species still occurred as far north as the mountains of sw. New Mexico and se. Arizona.
No historic nesting records are known for the Thick-billed Parrot north of the Mexican border, but this absence could easily have been an artifact of a lack of searching for nests during the period in which the species still occurred regularly in the United States, of the species' high-elevation nesting habits, and of its unusually late breeding season (Snyder et al. 1994). The species was recorded on a nearly annual basis in the Chiricahua Mountains of Arizona in the early 1900s, strongly suggesting that it was an established breeder in this location. In releases of Thick-bills in Arizona between 1986 and 1993, breeding records were obtained both along the Mogollon Rim and in the Chiricahuas (Snyder et al. 1994), clearly indicating the capacity of the species to breed this far north. The nearest known breeding population in Mexico lies in sight of the Chiricahuas, only 80 km south of the border.
Unfortunately, the Thick-billed Parrot suffered heavily from shooting in the United States and was very likely extirpated north of the border by this stress (Snyder et al. 1994). Populations have also declined markedly in Mexico, and the species has been considered Endangered by the International Council for Bird Protection (now Birdlife International) and the U.S. government since the late 1970s (King 1977b, U.S. Fish and Wildlife Service 1977a). The Thick-bill is also listed in Appendix 1 of CITES. Much of the recent decline is surely due to massive logging of the pine forests of the Sierra Madre Occidental since World War II (Phillips et al. 1964a, Lanning and Shiflett 1983, Lammertink et al. 1996), but the species has also been stressed by trapping for the pet and avicultural trades (Snyder and Wallace 1987). The Thick-billed Parrot is not limited to virgin forest, and can exist in selectively logged areas as long as snags suitable for nesting are available and these areas remain free of shooting and trapping.