Ll. Getz et al., NATAL DISPERSAL AND PHILOPATRY IN PRAIRIE VOLES (MICROTUS-OCHROGASTER) - SETTLEMENT, SURVIVAL, AND POTENTIAL REPRODUCTIVE SUCCESS, Ethology, ecology and evolution, 6(3), 1994, pp. 267-284
We analyzed the costs and benefits of natal dispersal and philopatry i
n a free-living population of the prairie vole, Microtus ochrogaster,
in which 70% of the males and 75% of the females were philopatric. Rat
her than settling into a nest, 40% of male dispersers continued to wan
der throughout the study area, while only 13% of female dispersers did
so. Whereas males were more likely to wander in spring-early autumn d
uring low density periods, females were more likely to wander during s
pring-early autumn, irrespective of population density. Of those anima
ls that settled into a nest, females were more likely than males to se
ttle as single individuals. Same-sex siblings that dispersed commonly
joined the same social group. Although often settling within 5 m of ea
ch other, opposite-sex siblings that dispersed never joined the same s
ocial group or formed a male-female pair. Total length of life was lon
ger for males and females that dispersed than for those that remained
at the natal nest. Animals survived longer after dispersal if they set
tled greater than or equal to 30 m from the natal nest than if they se
ttled less than or equal to 30 m from the natal nest. Length of surviv
al following dispersal was not correlated with age at time of dispersa
l. Fitness of female dispersers was 2.5 times that of philopatric fema
les, estimated by comparison of the percent becoming reproductive, sur
vival time after becoming reproductive, and the estimated number of fe
male offspring per litter that survive to adult age. The success of di
spersers may be related to the high food resource habitat in which the
study was conducted.