Monitoring a Pronghorn (Antilocapra americana mexicana) Population Reintroduced to the North-East of Mexico

Abstract

The pronghorn (Antilocapra americana mexicana), an endemic ruminant species of North America is classified as an endangered species. This study covering three years (1995-1998) was conducted 10 evaluate the factors determining the success of the re-introduction of pronghorn in the Mexican state of Coahuila. Vegetation characteristics, botanic composition of the pronghorn diet and birth and mortality rates were monitored. One hundred and seventeen vegetation species belonging to 32 different species were identified. Greatest diversity was obtained in the natural grass community (0.77), followed by halophyte grass community (0.74) and rosetophyll shrubs (0.53). Fifty-nine vegetation species were identified in the pronghorn diet and the poisonous plants: Solanum rostratum and Solanum eleagnifolium were determined in the pronghorn diet all-year round, though percentages consumed varied with season (0.96 % in wet season versus 11.2% in dry season). Of the total diet consumed by the pronghorns, forbs ranked highest (75%) while grasses and shrubs were consumed in almost similar quantities (12.5% of each). Births averaged 0.17 +- 0.075 and 4 and 3 deaths were recorded in 1996 and 1998, respectively. Competition with cattle for grazing would occur under drought conditions. It is concluded that the pronghorn will continue to be endangered despite these translocation programs. Further studies to evaluate supplementation strategies during critical times, to promote forb development and the dynamics of interaction with other ruminant animal species in the same rangeland, are necessary.