REPRODUCTIVE SUCCESS OF SOLITARILY AND COMMUNALLY NESTING WHITE-FOOTED MICE AND DEER MICE

To determine the fitness consequences of communal nesting in white-footed mice, Peromyscus leucopus, and deer mice, P. maniculatus, I compared the reproductive success of field populations of females nesting solitarily, in communal groups of more than one female, in extended families of successive litters, and in communal groups with extended families. Mean first litter size of weanlings and juveniles greater-than-or-equal-to 6 weeks old did not differ significantly for pups raised under the four nesting situations. Similarly, for pups born into extended families, litter sizes of pups from second litters did not differ significantly from those of first litters or from pups born to solitarily nesting females. Delayed dispersal of juvenile females did not result in resource competition or inhibition of reproduction. Thus, reproductive success of females was not significantly affected by additional members in the nest. At least 26 of 28 communally nesting females were close relatives. Solitary nesting is the common breeding pattern in Peromyscus, and extended families and communal nesting are alternative reproductive tactics in response to limited space, delayed dispersal, and local grouping among related females.