| Abstract: | I studied the behavior of nursing house mice (Mus musculus) in captivity and used a two-by-two factorial design to test the hypothesis that the combination of a protected nest along with a chance for the intruders to retreat would improve the ability of resident females to defend their litters from infanticidal males. A chance for the intruder to retreat was manipulated by testing the resident females in either a single- or a two-compartment cage. The effect of a protected nest was examined by providing females with a nest box having a narrow entrance. During each test, an infanticidal adult male was introduced into the cage of a resident female and her pups. I observed that neither the presence of a protected nest nor the chance for the intruders to retreat to a different compartment, or a combination of the two, increased the ability of a female to defend her litter against an intruder male. Moreover, neither of these two factors influenced the overall behavior of the resident females. I obtained similar results after using data from previous studies to examine the influence of both of these factors on the efficiency of maternal aggression. Overall, these two approaches showed that females are often unable to prevent intruders from committing infanticide. I discuss the validity of the hypothesis that maternal aggression evolved as a mechanism to protect offspring from infanticide. Aggr. Behav. 24:385–396, 1998. © 1998 Wiley-Liss, Inc. |
