the great curassow (Crax rubra). Relatively abundant species include Actitus macularia, Dendrocygna autumnalis, Egretta caerulea, Egretta thula, Tachybaptus dominicus and Coragyps atratus, all of which are associated with bodies of water. There have been 53 species of mammals detected recently in the park, of which two are considered threatened, two in danger and two subject to special protection. Endangered and threatened species include the spider monkey (Ateles geoffroyi), jaguarundi, ocelot, lowland paca, white-tailed deer, anteater (Tamandua tetradactyla) and buzzard (Sarcoramphus papa). The most abundant species include the bat Artibeus jamaicensis and the rat Peromyscus mexicanus. National park Establishment of the park The Sumidero Canyon National Park has its origins in a Chiapas state decree issued in 1972, which made the area around the canyon an ecological reserve to preserve its geology, history and wildlife and to allow for scientific study. For similar reasons, the park was taken over and enlarged to 21,789 hectares by the federal government in 1980. Most private landholders in the area were compensated for their lands, but not all resident persons or businesses were evicted. Since that time, the park has been under the administration of various agencies such as SAHOP, SEDUE and SEMARNAP, with the current managers being the Comisión Nacional de Áreas Naturales Protegidas and the Secretaría de Educación Pública. In 2004, the park came under the protection of the Ramsar Convention due to the importance of its ecology and water systems. It was also named a Región Prioritaria Terrestre and an Área de Importancia para la Conservación de las Aves by the Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO) in 2000. In 2005 and 2006, this agency enlarged the park again with the expropriation of lands in the municipalities of San Fernando and Tuxtla Gutiérrez, adding a total of . It remains, however, smaller than most other national parks in Mexico. The center of the park is the Sumidero Canyon and the Grijalva River that runs from south to north through it. The park's borders on this river are marked by the Belisario Domínguez Bridge, over which the Pan-American Highway runs, in the south and the Chicoasén Dam, to the north. The rest of the park's borders extend into the municipalities of Tuxtla Gutiérrez, Chiapa de Corzo, Osumacinta and San Fernando. This territory is mostly located in the Central Valley region of the state. The park is open 365