干旱区生态环境知识资源中心

Habitat lost and fragmentation can result in an isolated and local extinction risk for small populations like Ovis canadensis weemsi Goldman, 1937, in Sierra del Mechudo, Baja California Sur, Mexico. That is why it is important to evaluate the relationship between species and their habitat in order to design management and conservation plans. The object of this study was to evaluate structural elements of the habitat, Land Ruggedness Index (LRI) (escape terrain) and vegetation structure (visibility), which are determinant in anti-predator behavior of bighorn sheep. We made an analysis of use-availability of terrain types according to their LRI, and height and cover were measured from the perennial vegetation in three representative areas from the Sierra. Five different types of terrain were established and significant differences between use and availability were found, medium mountain ranges with ravines, high mountain ranges with canyons, and high mountain ranges with small canyons within big canyons were selected. Perennial vegetation is spaced with an average height of 1.3 m and 21% of cover, which means a good visibility for bighorn sheep. Besides evaluating sheep population and distribution periodically, considering the increase of human activities in the area, it is advisable to evaluate the structural habitat all along the Sierra del Mechudo. By evaluating the LRI, it would be possible to locate sensitive or critical areas that are important for management and conservation of bighorn sheep at least above 300 m in elevation.