Population density and use of space by Kerodon rupestris: An endemic and threatened rodent in the semiarid areas of Brazil

Abstract

Population density and use of space by the rodent, Kerodon rupestris, were investigated in a semiarid area in Brazil. Distance sampling was used along line transects to estimate population density. Observations of K. rupestris were recorded on rocks, open ground, and in vegetation. The air temperature and the height of the vegetation were recorded for each observation. The frequencies of these observations were analyzed using generalized linear models. A total of 612 observations were made for K. rupestris (in 23,172 m traveled), resulting in an estimated population density of 12.45 individuals/ha. Individuals were mostly observed on rock (71%), reflecting a dependence on rocky outcrops in the environment. The rodent was observed to be active when temperatures ranged between 23 and 45 °C, but was most active at temperatures ranging from 31 to 34 °C. Kerodon rupestris varied in its use of vegetation of different heights, preferring vegetation of up to 2 m in height. Our results indicated high density of K. rupestris in the study area, due to the preference for refuges formed by the prevalent rocky outcrops. The rodent displays characteristics typical of the island syndrome, namely being active on rocks and in vegetation, with activity influenced by temperature.