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Terrestrial Vertebrates of the Pueblo Nuevo Area of Southwestern Durango, Mexico

1962; University of Notre Dame; Volume: 68; Issue: 2 Linguagem: Inglês

10.2307/2422738

1938-4238

Robert G. Webb, Rollin H. Baker,

Amphibian and Reptile Biology

Amphibians, reptiles and mammals were collected in June and July, 1960, from El Salto southward to Pueblo Nuevo, southwestern Durango, Mexico. Collecting stations were established in four habitats designated as Boreal Forest, Pine-Oak Forest, Mixed Boreal Tropical, and Tropical Deciduous Forest. The last two habitats memtioned occur in one of the numerous large barrancas or canyons that dissect the irregular plateau of the Sierra Madre Occidental. Habitats of Boreal Forest and Pine-Oak Forest occur on the plateau. This report emphasizes the change in kinds of vertebrates with decreasing altitude in the barranca, and the increasing resemblance of the vertebrates to those of the arid tropical lowlands of the Pacific Coast. Many species occurring in Durango are certainly found only in the lower elevations of the barrancas, and have extended their ranges eastward into western Durango from the coastal lowlands, owing to the continuance of suitable habitats provided by the deep barrancas. In addition, these protected barrancas provide habitat for some animals characteristic of humid tropical environments found to the southward rather than to the westward along the Pacific Coast of Sinaloa and. northern Nayarit. Herein, five kinds of amphibians, six kinds of reptiles, and seven kinds of mammals are recorded for the first time from the state of Durango. The Sierra Madre Occidental in western Durango consists of a broad, irregular plateau at least 8000 feet in elevation with a few peaks rising as much as 2500 feet above this general level. The mountains, especially on the western side, are dissected by numerous, deep barrancas or canyons that contain tributaries of rivers that flow westward into the Pacific Ocean. These spectacular barrancas, some more than 4000 feet in depth, often are bordered by steep-sided walls of massive rock. The biota of this mountainous area is equally dramatic. Habitats at the higher elevations -on the rims of the barrancas contain boreal plants and animals. Habitats at the lower elevations in the narrow depths of the barrancas -contain tropical and subtropical species. From 19 July through 28 July 1960, a field party from Michigan State University collected terrestrial vertebrates in southwestern Durango, southward from El Salto (23046'N and 105?22'W) to the vicinity of Pueblo Nuevo (23030'N and 105023'W). A rough road, used principally to haul pine logs to the lumber mill at El Salto and totransport agricultural products (i.e., aguacate, mangos, coffee) to market, leads from El Salto to Pueblo Nuevo, a distance of approximately 48 miles by road but only 24 miles airline. This road winds through mountainous country at elevations of more than 8000 feet for approximately 42 miles before descending rapidly by a series of