Estrutura populacional de capivaras na estação ecológica do Taim, Brasil, RS

Abstract

A capybara population (Hydrochoerus hydrochaeris) was monitored in a borderline region between Taim Ecological Station and southernmost areas of rice cultivation located in the State of Rio Grande do Sul (RS, Brazil). The aim of this study was to characterize the structure, density, and reproductive periods of this population. A total of 25 censuses, obtained through direct count technique, were performed from August 2003 to August 2005. The samplings were performed in a 4000-meter length transect on the margins of Mangueira lagoon. The abundance was obtained considering the sex and age class of the animals. The abundance registered was of 608.6±27.9 individuals, and the average density was 5.1±0.2ind. ha-1. A variation in number of animals was observed between the first and the second year of sampling. This number was significantly higher in the last year. An average of 22.0±0.8 groups was identified in the sampling area, including female adults (47.5%), juveniles (24.8%), young (17%) and male adults (7.7%). The abundance of animals varied according to spatial distribution, and its highest value (9.5ind. ha-1) was registered in Taim Ecological Station. Seasonal fluctuations in the population recruitment were also observed during this study. The highest densities of young were registered in autumn. Population structure was similar to those registered in different areas of distribution, but it has presented a high potential of population growth.