B. Mcguire et Ll. Getz, THE NATURE AND FREQUENCY OF SOCIAL INTERACTIONS AMONG FREE-LIVING PRAIRIE VOLES (MICROTUS-OCHROGASTER), Behavioral ecology and sociobiology, 43(4-5), 1998, pp. 271-279
Hypotheses relating the behavior of voles to their population cycles o
ften assume that the rate of social interaction increases with populat
ion density. To test this assumption, we examined the frequency of soc
ial interactions in a population of prairie voles (Microtus ochrogaste
r) over a 7-year period. In addition, we characterized space use by re
sident animals, patterns of visitation by nonresidents to nests, and p
articipants in social interactions. Social groups within the populatio
n typically displayed little overlap in their use of space, even at hi
gh population densities. Nevertheless, nonresidents, particularly wand
ering males, were captured as visitors at nests. The number of visits
per social group did not increase in a simple linear manner with popul
ation density and was particularly variable when there were fewer than
100 animals/ha. At such times, more single females and fewer pairs re
ceived visits from males than expected based on the frequency of occur
rence of these groups in the population; a similar pattern was noted d
uring periods of high population density (greater than or equal to 100
animals/ha) but the comparisons failed to reach statistical significa
nce. Furthermore, at high population density, more communal groups rec
eived visits from females than expected. Patterns of visitation to com
munal groups were influenced by the number of adult male residents (wi
nter only), but not by the number of adult female residents or presenc
e of philopatric female offspring. These data indicate that the freque
ncy of social contact in prairie voles does not increase linearly with
population density and is influenced by the spacing and possible mate
-guarding behavior of resident animals.