Lawson pers. comm., Leopold 1937). 



NESTING AND BEDDING 



The only occupied nests reported were in cav- 

 ities high up in large dead pines in the Sierra Madre 

 Occidental of Chihuahua, at least some of which 

 were abandoned imperial woodpecker nests 

 (Thayer 1906, Bergtold 1906). According to resi- 

 dents in southeast Coahuila, they used cliffs and 

 possibly trees for nesting. There are few suitable 

 trees, but many cliffholes in the region (Lanning 

 and Lawson, pers. comm., Burleigh and Lowery 

 1942); they slept in higher cliffs of high barranca 

 at Palmito, Sinaloa, during May 1964 (R. Crossin 

 pers. comm. to W. King 1977). In the morning, 

 flocks leave the roost in the rimrocks in Sierra 

 Madre of Chihuahua (Leopold 1937). Eggs were 

 found (10 records) 10 May to 25 Aug. 1905 and 

 (7 recoids) 11 to 25 Aug. (Thayer 1906, Bergtold 

 1906, Bent 1940). They are not dependent on 

 holes made by the nearly extinct imperial wood- 

 pecker for nesting. Parrots are capable of re- 

 modeling a natural cavity or hole (Ridgley WWF 

 Report , Charles Hanson pers. comm. 1977). 



RITUAL REQUIREMENTS 



The courtship display, raising the wings to 

 expose under surfaces, may effect reproductive 

 isolation of pachyrhyncha and terrisi, because of 

 the marked difference in color of under primary 

 coverts. This display is accompanied by distinc- 

 tive vocalizations (Charles Hanson pers. comm. 

 1977). The habit of soaring in circles high in the 

 air like a hawk has been noted in both R. p. 

 pachyrhyncha and R. p. terrisi (Marshall 1957, 

 Ridgley WWF Report); in terrisi, the purpose is to 

 gain altitude for long flights (Lanning & Lawson 

 pers. comm.). When flying in flocks grouped by 

 pairs, two birds fly very close together, occasion- 

 ally with a third behind. Several feet separate pairs; 

 sometimes flocks fly in V-formation. They are 

 very noisy and their cries carry great distances, 

 probably facilitating communication between 

 wide-ranging individuals (Marshall 1957). 



OTHER CRITICAL ENVIRONMENTAL 

 REQUIREMENTS 



None known other than those given under 

 food, nesting and bedding, and habitat. 



POPULATION NUMBERS AND TRENDS 



R. p. pachyrhyncha. - Apparently is much re- 

 duced from Its former population; it is seen less 

 frequently and in smaller numbers in the heart of 

 its range in the Sierra Madre Occidental and no 

 flights have been observed in the southwestern 

 U.S. since the early 1900's. Pubhshed estimates 

 include 100 at Palmito, Sinaloa, 7 May 1964; 200, 

 same place, 10 May (R. Crossin pers. comm.), 

 flocks of 60 and 1 5 , at Volcanes de Colima, Jalisco, 

 6 Jan. 1973 (Schnell et al. 1974); about 300 in 

 the Chiricahua Mts., Ariz., 1 Sept. 1917; 100- 

 1500, same place, early fall, 1917; 150, same 

 place, middle of May through summer and early 

 faU 1917 (Wetmore 1935); 35, Cumbre, Barranca 

 deCobre, Chihuahua, 13 May 1950 (Stager 1954); 

 Flocks of 50, 60 and 8 in the Sierra Huachinera, 

 Chihuahua, 1951 and 1952; populations shift 

 from year to year (Marshcdl 1957). During an ex- 

 tensive survey of northern Mexico 11 Oct. to 31 

 Dec. 1971 and 2 Mar. to June 1972, with consid- 

 erable time spent in thick-billed parrot habitats, 

 only a few were seen high overhead (R. Crossin 

 pers. comm. to W. King). 



R. p. terrisi. - There is not much evidence of a 

 total decline in numbers of this subspecies, since 

 its existence has been known only since 1947 and 

 recent estimates seem as high as earlier ones. How- 

 ever, because of its restricted range, it probably 

 never had a large population and a continually de- 

 creasing habitat would certainly result in a popu- 

 lation decline. Population estimates include 91 at 

 La Mesa de las Tables, Coahuila; 15 and 60 at 

 Cerro Potosi, Nuevo Leon (Ridgley WWF Report); 

 400 to 500, near Saltillo, Coahuila, 1977; esti- 

 mate on the order of 1500 in entire Saltillo, Coa- 

 huila area (Dirk Lanning pers. comm. to W. King); 

 count of 800 to 1000 in Southeast Coahuila, 4 

 April 1977, (Lanning & Lawson pers. comm.). 



REPRODUCTION 



Following are records of nests with eggs or 

 young of R. p. pachyrhyncha : Collected by W. W. 

 Brown at Colonia Pacheco and Colonia Garcia, 

 Chihuahua: 9 nests, all in holes in dead pines, 

 heights above ground 50-80 ft (15 to 24 m) av. 71 

 ft (22 m); depth of nest cavity 18 to 28 in (46 to 

 71 cm) av. 24 in (70 cm); width of cavity 6-10 in 

 (15 to 25 cm) av. 8 in (20 cm); diameter of en- 



