Estudio poblacional de roedores en un bosque de pino del Eje Neovolcánico Transversal Mexicano

Abstract

DEMOGRAPHY AND REPRODUCTION OF THREE CRICETINES (N. ALSTONI, P. MANICULATUS AND R. MEGALOTIS) AND ONE ARVICOLID (M. MEXICANUS) WERE STUDIED IN A PINE FOREST ON THE TRANSVOLCANIC BELTNEAR MEXICO CITY. N. ALSTONI SHOWED CONSISTENTLY THE HIGHEST POPULATION DENSITY (9-57 IND./HA), FOLLOWED BY M. MEXICANUS (6-48 IND./HA), P. MANICULATUS (1-30 IND./HA) AND R. MEGALOTIS (0-10 IND./HA), RESPECTIVELY. THE FOUR SPECIES SHOWED A SIMILAR SIGNIFICANTLY CORRELATED FLUCTUATION OF POPULATION DENSITY. POPULATION PEAKS WERE OBSERVED AT THE END OF THE DRY SEASON (MARCH THROUHG MAY 1978) AND DECREASED GRADUALLY TO THE END OF THE RAINY SEASON (OCTOBER 1978), N. ALSTONI HAD THE HIGHEST SURVIVORSHIP (--- 12 MONTHS) AND NO SIGNIFICANT DIFFERENCES WERE OBSERVED BETWEEN P. MANICULATUS AND M. MEXICANUS (6.8 MONTHS). R. MEGALOTIS HAD THE LOWEST SURVIVORSHIP (---4 MONTHS). JUVENILES REACHED LOW DENSITIES (--10 IND./HA), AND CONSTITUTED A LOW PERCENTAGE OF THE POPULATION (--- 20%). ONLY A FEW YOUNG OF THE YEAR INITIATED REPRODUCTION IN N. ALSTONI AND M. MEXICANUS, AND NONE OF THE OTHER SPECIES. REPRODUCTIVE PEAKS IN P. MANICULATUS AND R. MEGALOTIS WERE OBSERVED DURING THE RAINY SEASON. N. ALSTONI AND M. MEXICANUS REPRODUCED THROUGHOUT THE YEAR. N. ALSTONI SHOWED A HIGHER PROPORTION OF LACTATING FEMALES AND HAD MORE LACTATING PERIODS PER YEAR (20-80%; 0-4) THAN M. MEXICANUS (10-60%; 0-3) P. MANICULATUS (5-40%; 0-2) AND R. MEGALOTIS (0-25%; 0-1). INTERBIRTH INTERVALS WERE CONSIDERABLY LONGER THAN IN CRICETIDS OCCURING IN BOREAL OR ALPINE HABITATS. FINALLY, WE COMPARE OUR RESULTS WITH OTHER POPULATIONS DISTRIBUTED IN DIFFERENT HABITATS, AND CONSTRAST THE LIFE-HISTORY PATTERNS OF THESE SPECIES WITH OTHER CONGENERICS STUDIED IN STRONGLY SEASONAL ENVIROMENTS.