Abstract:
The availability of resources, their effect on
population density and territoriality, and the ways in which
these factors are interwoven with mating systems are
important determinants of small mammal space use. It is
often difficult to study these patterns in an integrated way,
however, especially because long-term data are needed but
not readily available. In this paper, we investigate effects of
population density, season and breeding status on home
range patterns of the promiscuous rodent Mastomys
natalensis using monthly capture-mark-recapture data
collected over 17 years in a 3-ha grid. Home ranges were
estimated using minimum convex polygons bounded by
trap locations, and home range overlap and visitation rates
were calculated as a measure of territoriality. As higher
population densities coincide with increased resource
availability, we predicted that home range sizes would
correlate negatively with density. Furthermore, as
M. natalensis is promiscuous and population densities are
generally high, we predicted that territoriality would be
low, and home range overlap would therefore be high.
Contrary to expectations the home ranges of female adults
increased with population density, although those of male
adults and subadults followed the expected decrease. Home
range overlap and visitation rates were generally high, and
increased significantly with population density. More
importantly, they were never lower than those of simulated
datasets consisting of randomly moved home ranges. These
results therefore suggest that M. natalensis displays a
complete lack of territoriality that is rarely seen in small
mammals but still meets predictions based on knowledge
of density and mating system.
