White-nosed coatis in Arizona: tropical carnivores in a temperate environment
Intraspecific variation in ranging and social behavior can be perplexing, but also provides an opportunity to assess which behavioral attributes are labile in the face of geographic variation in resources. White-nosed coatis (Nasua narica) are group-living carnivores of tropical origin that possess an unusual social system. In the resource- rich tropics, larger-bodied males are solitary, whereas females live in groups (“bands”) along with young of both sexes, but leave them to give birth and wean their young. Males often disperse socially, but not spatially. We studied coatis in the Chiricahua National Monument, Arizona, a resource-poor, arid, and highly seasonal landscape. Using live capture and radiotelemetry in conjunction with microsatellite DNA analyses, we found that Chiricahua coatis exhibited the species-typical pattern of solitary males and gregarious females. Young males left their natal bands as yearlings, and some were found as adults within their natal home range. On the other hand, home ranges were expanded greatly. Bands, and some males, focused their movements in areas several km2 in extent over periods of weeks or months but shifted those areas markedly among seasons. Some males followed the typical mammalian pattern of natal dispersal beyond their natal area. Rates of movement were higher and female associations appeared to be more flexible than in the tropics. Adult females sometimes ranged singly, not only around the time of parturition, but also when population density was low and occasionally otherwise. In addition, home range overlap was high among both sexes during some seasons, and female bands sometimes fused for prolonged periods. Core patterns of sociality are constant in both resource-rich tropical and resource- poor temperate populations, but coatis appear to make major adjustments in scale of movement and frequency of association in response to resource variation.