REASONS FOR CURRENT STATUS 



Cutting of mature mountain pine forests, de- 

 priving the birds of food and nesting sites, is the 

 primary cause of the decline of the thick-billed 

 parrot (Vincent 1967, Monson 1965, Ridgley 

 WWF Report, Crossin pers. comm., W. King 

 1977). 



Killing of birds and taking of eggs for food, 

 sport, or specimens is known to occur but is cer- 

 tainly of minor significance because of the inac- 

 cessibility of areas where these birds live and the 

 difficulty of finding nests (Ridgley WWF Report, 

 Crossin pers. comm., King 1977, Lusk 1900, 

 Wetmore 1935, Thayer 1906, and Bergtold 1906). 



Capture for zoos and for pets occurs but is 

 also a minor cause of decline (Lanning and Law- 

 son pers. comm., Crossin pers. comm.. King in 

 press, Wetmore 1935). Apparently, this species is 

 not used much in the commercial cage bird trade, 

 as it is not listed as imported into the U.S. in 

 recent years (Clapp 1975). 



Forest fires and logging are considered the 

 greatest potential threats to R. p. terrisi at present 

 in southeast Coahuila (Lanning and Lawson pers. 

 comm.). 



PRIORITY INDEX 



Not assigned. 



DESCRIPTION 



R. p. pachyrhyncha is mostly dull olive green; 

 the forehead, lores, and a stripe extending along 

 the sides of the crown, bend of wings, and thighs 

 are deep red; the tail is long and pointed, outer 

 feathers graduated. In flight, the bright yellow 

 patch on under-wing converts is conspicuous. 

 The bin is black and notably thick. The iris is red- 

 dish. R. p. terrisi is larger and darker green; the 

 forehead and supercilliary stripes are brownish 

 maroon (instead of bright red); the patch on the 

 underwing converts is brownish gray (not bright 

 yellow as in R. p. pachyrhyncha) (Blake 1953). 

 All color characters of pachyrhyncha and terrisi 

 are highly variable and not definitely distinguish- 

 ing, except color of under primary converts, 

 which are bright yellow in pachyrhyncha and 

 olive yellow in terrisi; terrisi is also larger (Hardy 

 and Dickerman 1955). All examples of terrisi seen 

 at close range in the field have had maroon rather 

 than scarlet foreheads, but five adults in the Uni- 



versity of Kansas collection have a few scarlet 

 feathers on forehead (Ely 1962). 



Length, 16 - 16.7 in. (41-42 cm); wing, 8.5 - 

 10.5 in. (22 - 27 cm); taU, 6.3 - 7 in. (16 - 18 cm); 

 bill length, 1.4 - 1.5 in. (3.6 - 3.8 cm);biU height, 

 1.6 - 1.7 in. (4-4.3 cm). Bill relatively very large 

 and greatly compressed laterally (Bailey 1938). 

 Weight: terrisi, SW, Coahuila, 2 males, 391.5 and 

 467.5 gms; female, same area, 466 gms (Urban 

 1959). 



Whether pachyrhyncha and terrisi are con- 

 sidered as two distinct species or two weU-marked 

 subspecies of a single species is a matter of opin- 

 ion. Prior to Dickerman and Hardy(1955) all au- 

 thors who reported specimens with mixed charac- 

 ters considered them 2 distinct species. Since then, 

 subspecific status has been accepted by Dicker- 

 man and Hardy (1955), Ely (1962), Forshaw 

 (1973), Urban (1959), Vincent (1967), and King 

 (1977). However, Hardy (1967) changed his 

 mind on the basis of the hypotheticail importance 

 of the difference in shade of red of the forehead, 

 which he thought might be significant in social 

 recognition of the birds belonging to the two 

 populations, serving as effective reproductive 

 isolating mechanisms, thus making them two dis- 

 tinct species by definition. 



RANGE 



R. p. pachyrhyncha formerly bred in high 

 coniferous forests in Sierra Madre Occidental of 

 western Mexico from northwestern Chihuahua 

 (Colonia Pacheco and Colonia Garcia, Thayer 

 1906) south to southern Durango (Canyon Rio 

 San Juan, Bent 1940), from 4,000 to 10,000 ft 

 (1,219 - 3,048 m) (Bergtold 1906). Within the area 

 reported from Sierra Huachinera (Marshall 1957), 

 Cumbre on Barranca Cobre, SW Chihuahua (Stager 

 1954), Mt. Mohinora, southwest of Verjel (Fried- 

 mann et al. 1950), mountains west of Parral (Berg- 

 told 1906), Guadalupe y Calvo (Bent 1940), all in 

 Chihuahua, and the mountains near Ciudad Dur- 

 ango (Bent 1940) in Durango. They formerly wan- 

 dered extensively, chiefly in winter, or when pine 

 cone crops failed, to mountains of southeastern 

 Arizona and southwestern New Mexico, and, cen- 

 turies ago, even to central and northern Arizona 

 (Verde Valley and San Francisco Mountain). The 

 chief areas visited included the Chiricahua Moun- 

 tains, and occasionally nearly all the higher moun- 

 tains east and south of the Santa Cruz and Gila 



