Spatial and social organization of the burrowing rodent Clyomys laticeps (Thomas, 1909)

Abstract

Burrowing rodents display diverse patterns of social organization, ranging from solitary to group living. Differences in social organization are often inferred from patterns of space use, particularly differences in the degree to which individual home ranges overlap. Here, we characterize patterns of space use in a poorly studied species of burrow-dwelling echimyid rodent, the Broad-headed Spiny Rat (Clyomys laticeps). Specifically, we use radiotelemetry studies of a free-living population in Parque Estadual da Serra de Caldas Novas (Goias, Brazil) to evaluate previous, apparently contradictory reports suggesting that this species is both solitary and social. A total of 20 adult (12 females, 8 males) C. laticeps were monitored via telemetry during two consecutive cycles of annual wet and dry seasons. The resulting data indicate that although overlap of individual home ranges was common, co-occurrence of adults in time and space was rare and was limited to male-female pairs, a pattern that is most consistent with a solitary lifestyle in which individuals occupy distinct burrow systems. Neither sex nor season affected spatial overlap; this outcome is consistent with evidence suggesting that reproduction in this species occurs throughout the year. Although home ranges for males were larger than those for females, areas occupied by both males and females overlapped with multiple opposite-sex individuals, making it difficult to determine from spatial data whether the study population was polygynous or polygynandrous. While genetic data are needed to characterize fully the mating system of these animals, our analyses provide the first detailed information regarding spatial relationships in C. laticeps, thereby allowing more accurate placement of this species within a larger, comparative behavioral framework and facilitating efforts to identify factors contributing to social diversity among burrow-dwelling rodents.