CONICET | Buscador de Institutos y Recursos Humanos

Capybara (Hydrochoerus hydrochaeris) is the largest living rodent, widely distributed in South America. In Argentina it is an important economic resource: free-living populations are commercially harvested for their meat and leather. However, little is known about its ecology and behavior. For this reason, between spring 2006 and winter 2007, we studied daily and seasonal activity patterns of a capybara population in Esteros del Iberá, in relation to air temperature. Using scan samples we surveyed each of 15 groups from dawn to dusk every 15 min recording air temperature. Daily activity was different according to time of day (X2=335.04; d.f.=45; p0.01), with animals being more active at dawn. The numbers of active individuals varied according to season (p0.05). In spring and summer we observed a bimodal pattern; in fall the autumn, it was unimodal, while in the winter we observed three activity peaks along the day during the winter. The numbers of active individuals varied was seasonally different varied seasonally (X2=8,029; d.f.= 3; p0,045). We observed more active individuals during the winter, then with fall, summer and spring being the season with less activity during the day. Daily activity was not related to daily temperature but we found significative regressions between the number of individuals (active and inactive) in habitats with water and daily temperature, with a better adjustment in the warmer seasons (spring-summer), while in the coldest days in fall and winter we did not find any relation between those variables. There was no relationship between capybaras´ activity and air temperature during summer and spring. We observed fewer active capybaras during the warmer hours in those seasons and lower daily activity. During fall and winter we found more active capybaras during the day and during the warmer hours of the day.

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