Sexual differences in spatio-temporal interaction among badgers

Abstract

I tested the following hypotheses of territorial polygyny on badgers (Taxidea taxus: Carnivora; Mustelidae): Competition among adult females for food should result in intrasexual territoriality, while male competition for females should result in larger territories that encompass multiple female territories. The sagebrush-grassland study area (Wyoming, USA) contained a depauperate terrestrial fauna with a dense badger population preying on high densities of ground squirrels (Spermophilus armatus). Implant telemetry generated locations for analysis of home range and spatio-temporal interaction. During the summer breeding season males doubled movement rates and nearly tripled home range areas to overlap those of females. Before and after the breeding season, males reduced their home ranges to sizes nearer those of stable female ranges ([Formula: see text]=2.82 km²). Unexpectedly, home range overlap between males and females was no different than intrasexual overlap. However, analysis of spatio-temporal interaction revealed that females spatially avoided one another, while males were spatially and temporally attacted to one another, similar to that of male-female interactions. Presumably, olfactory mechanisms allow resource tracking and lagged communication. Male-male territoriality was not viable, most likely because the high density of badgers, combined with the severely male-biased sex ratio (1.75:1), effectively increased intruder pressure - as a resource, receptive females were too mobile and spatially unpredictable within their home ranges. Consequently, males monitored and searched widely for relatively scarce females during the breeding season with the effect of attracting each other. Male mobility, home range size, and possibly aggression increased with age, suggesting age-related breeding tactics, although dominance could only be surmised. This and other studies suggest how the spatial, temporal, and dominance components of carnivore resource partitioning and sociality will be understood better by unraveling the interplay of olfactory processes, attributes of disparate resources (e.g., food vs. females), seasonality, and population density and age-sex structure.

Keywords: Carnivores; Home range; Intraspecific competition; Polygyny; Spatio-temporal interaction.