Before the risk that some species of animals and plants face due to the degradation and the loss of their habitats or because of the human activities which directly have reduced the size of their populations, some programs have been implemented since some years ago; such programs, by means of the reintroduction of specimens into their original habitats, allow the repopulation or the recovery of their populations. The Projects of Conservations and Recovery of Priority Species (PREP), the Program of Conservation of Endangered Species (Procer) and the Programs of Action for the Conservation of Species (PACE) are some instruments that have propelled such actions. Some species for which some specimens have been reintroduced for the recovery of their populations are:

• The California condor (Gymnogyps californianus): nowadays, the NOM-059-SEMARNAT-2010 classifies it in the category of endangered. The last seen wildlife specimen was seen in Mexico before its reintroduction program was implemented was in 1937. Its recovery started in 1999 within their native habitats of the Sierra de San Pedro Mártir, in Baja California. By mid-2012, there were 29 specimens counted, 23 in the wildlife and six waiting for their release.

• Mexican gray wolf (Canis lupus baileyi): early the 20th century, this carnivore inhabited the mountain regions of the states in the north and center of Mexico. Due to the intense campaigns for its eradication, propelled by the governments of Mexico and the United States, it was almost exterminated by the decade of 1970. The NOM-059-SEMARNAT-2010 identifies it in the category of probable extinct from the wildlife. In October 2011, the Conanp released, in Sonora, the first group of Mexican wolves (three females and three males) into one of the ecosystems that originally they inhabited; however, two months later it was confirmed that four specimens had been poisoned.

• Pronghorn (Antilocapra americana): this species was, until before the colonization in North America, very abundant in the prairies and plains of the south of Canada, west in the United States and north of Mexico. Due to the hunting and the destruction and fragmentation of its habitat, its populations reduced dramatically during the last century, until it was considered within the NOM-059-SEMARNAT-2010 in the category of danger of extinction. The first attempts of recovery in Mexico are from 1922 and consisted of the introduction and reintroduction in some states in the north. By 2006, the population was a little over a thousand specimens: about 200 of the peninsularis subspecies; 440 of the sonorienses and 400 of the mexicana subspecies. The program with the highest relevance has been the recovery of the peninsular pronghorn in the protected areas of El Vizcaino and the Valle de los Cirios, in the Peninsula of Baja California. This project allowed the increase of the population from less than 60 specimens in 1997, before the start of the recovery program to nearly 400 specimens in 2012.

• Bison (Bison bison): this herbivore occupied, 150 years ago, nearly a third part of the national territory, in the natural pastures of Coahuila, Chihuahua, Sonora, Durango and Zacatecas. Due to the indiscriminate hunting, the change of the pastures into farming lands and the diseases of the European cattle, among some other factors, their habitats disappeared in 1820 (List et al., 2007). In order to recover its populations and taking into consideration its important ecological role in the natural pastures, in 2009, in Janos, Chihuahua, it was carried out the release of 23 specimens genetically pure, coming from the Wind Cave National park, South Dakota in the United States (Conanp, 2009). Two years later, there were eleven births, with which the size of the reintroduced populations increased. Nowadays, it is listed as an endangered species according to the NOM-059-SEMARNAT-2010.

REFERENCES:

Ceballos, G., S. Blanco, C. González y E. Martínez. Distribución potencial de Antilocapra americana (berrendo). Proyecto DS006 “Modelado de la distribución de las especies de mamíferos de México para un análisis GAP”. Instituto de Biología, Universidad Nacional Autónoma de México. México. 2006.

Conabio. Fichas de especies prioritarias. Cóndor de California (Gymnogyps californianus). Conanp y Conabio, Semarnat. México. 2011.

Conabio. Fichas de especies prioritarias. Lobo mexicano (Canis lupus). Conanp y Conabio, Semarnat. México. 2011.

Conabio. 2011. Fichas de especies prioritarias. Berrendo (Antilocapra americana). Conanp y Conabio, Semarnat. México. 2011.

Conanp, Semarnat. Volvieron los bisontes a Chihuahua en el Día Nacional por la Conservación. Comunicado de prensa del 30 de noviembre de 2006. Disponible en:
www.conanp.gob.mx/difusion/comunicado.php?id_subcontenido=86. Fecha de consulta: mayo de 2012.

List, R., G. Ceballos, C. Curtin, P. J. P. Gogan, J. Pacheco y J. Truett. Historic distribution and challenges to bison recovery in the northern Chihuahuan Desert. Conservation Biology 21: 1487–1494. 2007.

Rojo. A., K. Santos del Prado y E. de la Cruz. La recuperación del cóndor de California en México. INE-Gaceta Ecológica 67: 33 – 44. 2003.