Temporal Use of Home Range by the Hispid Cotton Rat

Hispid cotton rats (Sigmodon hispidus) exhibit home ranges on daily and multiday time scales. Radiotelemetry was used to demonstrate that daily use of the multiday home range was not random, but systematic; daily home ranges were occupied in a clockwise pattern within the multiday home range. Such systematic use of the multiday home range may result in more efficient foraging in habitats where required resources are distributed in a patchy fashion. To determine whether systematic use of the multiday home range was caused by behavioral interactions among conspecifics, an index of exclusivity was computed to reflect the amount of daily home range for each individual not overlapped by any other individual. Average exclusivity was 84% for the total population and 93% for same-sex pairs. Computer simulations that randomly positioned daily home ranges showed that observed exclusivities were significantly higher than expected, particularly among males during breeding seasons. Thus, biological interactions, probably territoriality, among males resulted in nearly total separation of home ranges and also may play a part in systematic use of the multiday home range.