ABSENCE OF RESPONSE OF ANT NUMBERS TO LIVESTOCK EXCLOSURE AT BAJA-CALIFORNIA-SUR, MEXICO

Ant numbers were compared between grazed and ungrazed tropical deciduo us forest using a 9,600 M2 two years old exclosure. During september 1 991, at a virtual island of vegetation, the Sierra de la Laguna, Baja California Sur, Mexico, we established inside the exclosure, a transec t system of 1,000 m2, which was paired with an equivalent transect sys tem outside the exclosure. During all diurnal hours of the consecutive days of last week of September 1991 we surveyed both transect systems for ants. We identified 5 species of ants, and found that any species responded to livestock exclusion in terms of the relative number of i ndividuals located on transects inside or outside the exclosure. Our r esults are discussed in terms of the food specialization of the specie s and the habitat characteristics.