Habitats, population densities, and social structure of capybaras (Hydrochaeris Hydrochaeris, Rodentia) in the Pantanal, Brazil

Abstract

Cleber I.R. Alhol Nelson L. Rondon 2 (1) The Pantanal is the central portion of a sunken flat plain bordering the upper Paraguay Tiver, with an area of 140,000 km 2. Seasonalfloods begin in January and end in ApTiI. From May to October tfl!! Iand dries out and campos (grassIand formations) and scattered pools appear. (2) Typical capylxzra habitat in the Pantanal is composed ofthree components: the water, a patch of forest, and a grass field for foraging. Highest densities of capy lxzras (14 individuais jkm 2) were found during the rainy season when the avaiIable spoce for capylxzras was reduced due to the flooding. Areas without ponds or creeks presented low densities (from 0.38 to 0.84 capylxzrasjkm 2). Group sizes ranged from 2 to 49 individuais ("X = 9.48). (3) Reproduction occu"ed year-round and young of differem ages were seen throughout the year. However, the principal recruitment of young to the population was observed in JuJy-August. Wlúle the females took tums in caring for young of different ages, probably the offspring ofmothers who are sisters in the same social groups, the males competed intensively with each other for access to breeding females. The males reproductive success appears to be ümited to the number of breeding females that males have access to in the social group.