SONORAN PRONGHORN Antilocapra americana sonoriensis (Goldman) 



Order: ARTIODACTYLA Family: ANTILOCAPRIDAE 



Distinguishing characteristics : A small, pale pronghorn, similar to the Mexican 

 pronghorn (A . a . mexicana) , but considerably smaller and differing in cranial details . 

 Smaller and paler than either A . a . americana and A . a . peninsularis . 



Present distribution : Found in the United States only in a limited portion of the Cabeza 

 Prieta Game Range and the Organ Pipe Cactus National Monument, Arizona. Present 

 Mexican range is unknown, but believed to be confined to northwest Sonora from about 

 100 miles northwest of Hermosillo north to the Pinacate region. 



Former distribution : Desert plains of central western Sonora and north to southern 

 Arizona . 



Status : Reduced in range and numbers; possibly holding its own in Arizona, but 

 probably rapidly decreasing in Sonora. 



Estimated numbers : In 1968, about 60 on the Cabeza Prieta Game Range and 15 on 

 Organ Pipe Cactus Monument. According to Bernardo Villa R. , following a survey in 

 1957, about 1,000 were then left in Mexico. 



Breeding rate in the wild : Usually 1 kid per doe annually; sometimes 2. 



Reasons for decline : Competition from domestic cattle and horses . Overshooting and 

 poaching, especially in Mexico in recent years. Predation on its reduced numbers. 



Protective measures already taken : Establishment of Cabeza Prieta Game Range and 

 Organ Pipe Cactus National Monument. Mexican Government is taking protective 

 measures . 



Measures proposed : Establishment of an international game range . Research into the 

 animal's ecologic needs. 



Number in captivity : None . 



Breeding potential in captivity : Probably fair . 



Remarks: Small numbers on American side are dependent for survival on the existence 

 of a larger nucleus on the Mexican side; in some years, none are found on the American 

 side. This makes it a mammal of international interest, and its management must depend 

 on international cooperation . 



References : 



Narrative reports of the Cabeza Prieta Game Range (Bureau of Sport Fisheries and 



Wildlife files), 1939— present . 

 Goldman, E. A. 1945. A new pronghorn antelope from Sonora. Proc . Biol. Soc . , 



Washington, Vol. 58, p. 3. 

 Villa R . , Bernardo . 1958 . Informal report on studies of bighorns and antelope 



in northern Mexico . Institute de Biologia, Mexico, D.F. 



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