BRANTA — Roberto Salazar-Aragón
Population assessment, habitat use and ecology of the West Mexican Chachalaca (Ortalis oliocephala) in Chamela, Jalisco
Institution: National Autonomous University of Mexico
Supervisors: Jorge Vega
Details: MSc, 2016
Email
Subject Keywords:Chachalacas, distance sampling, habitat use, tropical dry forest, Cracidae, Mexico
Species Keywords: West Mexican Chachalaca (Ortalis poliocephala)
Abstract
POPULATION DENSITY OF THE WEST MEXICAN CHACHALACA WAS ESTIMATED FOR 9 SURVEY SITES LOCATED IN THE CHAMELA-CUIXMALA BIOSPHERE RESERVE, AS WELL AS FOR THE DIFFERENT VEGETATIONS AND LAND USES FOUND WITHIN THE RESERVE. BOTH KIND OF ESTIMATIONS WERE DONE FOR THE DRY AND RAINY SEASON SEPARATELY. THE HIGHEST DENSITY WAS ESTIMATED FOR THE CHAMELA BIOLOGY STATION (5.8 & 5 IND/HA IN THE DRY AND RAINY SEASON, RESPECTIVELY). ON THE OTHER HAND, THE DENSITY ESTIMATED FOR THE PRISTINE TROPICAL DRY FOREST (5.2 & 2 IND/HA FOR THE DRY AND RAINY SEASON, RESPECTIVELY) AND THE SECONDARY TROPICAL DRY FOREST (3.3 & 1.3 IND/HA FOR THE DRY AND RAINY SEASON, RESPECTIVELY) WERE HIGHER THAN FOR THE REST OF THE VEGETATIONS/LAND USES. ADDITIONALLY, THE DENSITIES OF THE WHOLE RESERVE ESTIMATED BY LINE TRANSECTS AND POINT COUNTS WITH PLAYBACKS WERE COMPARED, USING THE DATA FROM THE RAINY SEASON ONLY. ALTHOUGH THE DENSITIES (1.6 IND/HA FOR TRANSECTS AND 1.1 IND/HA FOR POINT COUNTS WITH PLAYBACKS) DID NOT SHOW A STATISTICALLY SIGNIFICANT DIFFERENCE, THE DENSITY ESTIMATED BY TRANSECTS WAS HIGHER.
A GOODNESS OF FIT CHI SQUARE TEST WAS PERFORMED FOR BOTH SEASONS IN ORDER TO DETERMINE IF CHACHALACAS SHOWED A DISPROPORTIONATE USE OF THE VEGETATIONS/LAND USES WITHIN THE RESERVE. DURING THE DRY SEASON, CHACHALACAS PREFERRED THE SECONDARY TROPICAL DRY FOREST, WHILE AVOIDING THE AGRICULTURE, URBAN, AND LIVESTOCK LANDS. DURING THE RAINY SEASON, CHACHALACAS PREFERRED BOTH THE PRISTINE AND SECONDARY TROPICAL DRY FOREST, WHILE AVOIDING THE SAME LAND USES.
FOR BOTH SEASONS, CORRELATIONS BETWEEN POPULATION DENSITY AND FRAGMENTATION PARAMETERS (NUMBER, MEAN SIZE, DENSITY AND DISTANCE BETWEEN PATCHES, AS WELL AS PERCENTAGE OF FOREST COVER) WHERE PERFORMED. THERE WAS NO SIGNIFICANT CORRELATION BETWEEN THESE PARAMETERS AND THE POPULATION DENSITY, ONLY BETWEEN THE PERCENTAGE OF FOREST COVER AND THE EFFECTIVE DETECTION RADIUS, SHOWING A DECAY OF SUCH RADIUS AS THE FOREST COVER INCREASES (R2 FOR THE DRY SEASON = 0.76, R2 FOR THE RAINY SEASON = 0.45).