Male identity and enclosure size affect paternal attendance of meadow voles, Microtus pennsylvanicus

Abstract

Paternal care in meadow voles, Microtus pennsylvanicus, was compared (1) for sires of the litter and non-sires, (2) in the presence and absence of a second male on the other side of a wire partition, and (3) for voles housed in laboratory cages or larger enclosures. Paternal attendance was assessed by the amount of time males spent with pups, and the effect of this care on pup survival and weight gain was observed. In both small cages and large enclosures, sires spent more time with pups than did non-sires, and the presence of a non-sire across the partition reduced the sire's paternal attendance. In small cages fewer pups survived in the non-sire group than in the sire group, but in the enclosure pup survival was high for all groups. Males in all groups approached the nest equally often, but females attempted to prevent nest entry by nonsires. Pup weights were lower when a non-sire was on the other side of the partition. When a non-sire was present instead of, or in addition to the sire, the amount of male attendance was reduced. This is consistent with the pattern of pregnancy disruption for this species, suggesting that pregnancy disruptions may function to limit female investment in a litter when male investment is likely to be low. Since litters with sires gained more weight than litters housed only with females, and since paternal attendance by sires remained high when voles were housed in large enclosures, functional paternal care may contribute to the reproductive success of meadow voles.