Thick·billed Parrots

Abstract

That the Carolina parakeet was a native American parrot there is no doubt. Its history of occurrence in the southeastern United States at least was well documented, while the story behind its decline to extinction is speculative at best. Only one other parrot, the Thick-billed Parrot (Rhynchopsitta p. pachyrhyncha) has occasionally journeyed into the southern part of the United States, at the northern boundary of its range which is generally the highlands of northern and central Mexico. It is said that the Thick-bills once occured as far north as northern Arizona in their search perhaps for pine seeds in the forests that capped the mountain ranges of the southwest.

Thick-billed Parrots are bright green in color with the forehead, fore-crown and stripe above the eye a bright red, as are the bend of the wing, carpel-edge and thighs. With its wings outspread, the underwing coverts show yellow while the underside of the flights and tail feathers are grayish. Bill is black and the iris is orange-yellow. A distinct subspecies known as the Maroonfronted parrot (R. p. terrisi) lives in southeastern Coahuila, Mexico. Where the Thick-billed is red on the head, the Maroon-fronted is a maroon brown and is somewhat larger in size.

The mountains of southeastern Arizona provide ideal habitat for the Thick-bills, albeit at the edge of their range. And as is the case with most animal populations, the distributional perimeter is seldom static, but ebbs and flows like water on a coastline. The mountains of southeastern Arizona rise from the desert floor to an elevation of over 9,000 feet. Although this region of the United States is a mosaic of plant communities, the preferred habitat of the Thick-billed Parrot is the pine forest. It has always been an erratic visitor, mainly, in winter, to the mountains of the southeastern part of the state. But with the rapid clearance of pine forests over the major portion of its northern range in Mexico and elsewhere, the Thick-bills former abundant numbers have decreased.

During 1917-1918, in the Chiricah ua mountains of Cochise County, Arizona,

there was an invasion of about 1,000 Thickbilled Parrots. These birds consumed large quantities of the seeds of Chihuahua pines (Pinus chicuahuana) and then switched to acorns when the pine crop was exhausted. As a graduate student on field investigations in southern Arizona between 1960-1963, I was on the lookout for such avian wanderers and although the copperytailed Trogons, an uncommon sight, were seen, and the only cotinga to venture north of the border, the Rose-breasted Becard was noted, the Thick-billed was not encountered. It is likely that the large flocks sighted during the early part of this century, represents the last large-scale invasion for this species in the United States.

In nature, Thick-bills live primarily on the seeds of pine trees (genus Pinus) but also consume acorns, fruits and other vegetable matter. They nest between the months of May and August in holes of pine trees high off the ground, most likely utilizing old nests originally carved out by various species of woodpeckers.

At the San Diego Zoo, the Thick-billed Parrot diet consists of safflower and sunflower seeds, a variety of mixed grains (millet, canary, rnilo, wheat, oat groats), assorted greens (spinach, chard, dandelion, lettuce), and pieces of orange, apple, banana, papaya, chopped carrots and yams (of which the birds take little). Fresh corn on-the-cob, a few peanuts, and trout chow are also provided. Vionate vitamin/ mineral powder is provided on bread crumbs. Pine nuts are offered when available.

The hatching and rearing of Thick-billed Parrots in capativity is not a common event. The first recorded breeding of this species in captivity occurred in 1965 at the San Diego Zoo. In March, 1955, a female was received from the Rudkins, wellknown southern California aviculturists, and a year later U.S. Customs Service donated a male Thick-billed to the Zoo. It was nine years before this pair was to undertake successful nesting. According to K.C. Lint, thencuratorofbirds, who wrote about this breeding in Zoonooz (1966), the

aviary in which the birds nested was 8 feet wide, 10 feet deep and about 10 feet high with a wooden box located at the top of the aviary measuring 14 inches wide and 24 inches long with a 6 inch opening. The box was half filled with pine shavings and soil. Courtship was observed to occur over about a 4 week period and included the male feeding the female and abundant vocaliz.ations, especially when the female was in the box calling to the male. On the day of 12 August, 1965, the female was observed to stay in the box, refusing to come out to feed as had been her usual pattern. However, the male flew to the box and fed her by regurgitation. On the basis of these observations, it is suspected that the female laid, on this date, a single white egg. Only the female was noted to incubate the egg. On8September, 1965, the egg hatched after an incubation of 28 days. Sixteen days later the chick was removed from the nest and was already developing conspicuous pin feathers. It was fed a diet for the next three months which was being offered to all young parrots, cockatoos and macaws; it is reprinted here for reader information.