Lowell L. Getz

Social Organization and Mating System of the Prairie Vole, Microtus Ochrogaster

A communal nesting group, formed by additions to a monogamous pair breeding unit, is the basic year-round social unit of the prairie vole, Microtus ochrogaster. Before communal groups form, presumed monogamous pairs display traits normally associated with monogamy including cohabitation of a common nest, a shared home range, and dissolution of the pair primarily by mortality of one or both members. When juvenile nest mortality was reduced during late autumn-winter, extended-family groups formed. There was no difference in natal dispersal between summer and autumn-winter. Approximately 70% of the animals added to monogamous-pair breeding units were philopatric young. Unrelated adults (30% of the additions) joined extended-family groups in equal proportions in summer and late autumn-winter. Approximately half of the unrelated adults were reproductive when they joined an extended family group. During periods of winter reproduction most winter communal groups included at least one reproductive male and female, approximately half included two or more reproductive males and females (half of these were unrelated adults).

Duration of postpartum estrus in the prairie vole

The present study was designed to delineate the duration of postpartum estrus in the prairie vole, Microtus ochrogaster. Breeding pairs were separated prior to parturition, and males were reintroduced to the females 0–12 h, 12–24 h, 24–48 h, or 48–72 h postpartum. Pairs were observed for 1 h to determine whether mating occurred. Eighty percent of females in the first two time intervals were receptive within 24 h of parturition, 60% of females in the third time interval mated with males 24–48 h postpartum, and only 10% of females in the final time interval mated 48–72 h following parturition. These results indicate that postpartum estrus in this species typically lasts only 24–48 h.

Estimating philopatry and natal dispersal of microtine rodents through intensive live-trapping at nests of social groups

Estimates of philopatry and natal dispersal of the prairie vole, Microtus ochrogaster, determined by intensive live-trapping at social group nests were assessed by comparison of estimates when a grid pattern within the area was also trapped, the periphery of the group home ranges was trapped, and when only a few and a large number of nests were being monitored. Several analyses confirmed that the measures of philopatry and natal dispersal were reliable. Although labor intensive, the protocol used is less so than any other system that provides comparable amounts of data, and it does not require expensive equipment.

Effectiveness of multiple-capture live traps for field behavioral studies of microtine rodents

Use of multiple-capture live traps in routine demographic studies provides data concerning social organization and potential interactions between individuals, data not otherwise available from single-capture traps. Multiple-capture traps are especially effective in field behavioral studies in which large numbers of animals occupying a single nest must be monitored at frequent intervals. Burt multiple-capture traps are shown to be at least as efficient as Longworth single-capture treadle traps in capturing both Microtus ochrogaster and Microtus pennsylvanicus.