Maternal aggression toward infanticidal males of different social status in wild house mice (Mus musculus domesticus)

Abstract

Maternal aggression was examined in wild female mice (Mus musculus domesticus) derived from animals trapped in Alberta, Canada. Lactating females were tested for their behavior toward intruder males during the time of postpartum estrus while housed in a two‐cage apparatus containing a defensible nest area. Prior to being used as intruders, sexually naive males were screened for their behavior toward a newborn pup (83% exhibited infanticide). Only infanticidal males were then housed in pairs and allowed to establish a dominance hierarchy. Dominance status was further verified by a urine marking test. The dominant and subordinate infanticidal males were then placed into a lactating female's cage and observed for 1 hr. The test was terminated immediately when a male began to attack the pups. Lactating females attacked the males in both groups, but subordinate males received more intense attacks than dominant males. Dominant males elicited significantly more fear/defense behavior than subordinate intruders. All of the dominant males and only one submissive male attacked the pups. Females were thus successful in blocking infanticide only by infanticidal subordinate males. Since females do not persist in attacking males with high fighting ability, one function of maternal aggression could be to assess the fighting, and resource holding, potential of a future mate. © 1994 Wiley‐Liss, Inc.

The scent of infanticide risk? Behavioural allocation to current and future reproduction in response to mating opportunity and familiarity with intruder

“…If the potential intruder is also a potential mating partner, as in our experiment, females must find a way to mate without endangering their dependent offspring, which they can achieve by mating away from the nest. In tree rats, we observed females engaging in matings with several males at a safe distance from the female’s nest (Eccard et al 2004) and following odour trails of males (MC Breedveld et al, personal communication), again indicating that females may actively distract mating partners from the location of their offspring (Palanza et al 1994; Jonsson et al 2002b; Ylönen and Horne 2002) rather than defending their nest from the inside.…”

“…Several counterstrategies among females against male infanticide have been identified (summarised in Lukas and Huchard 2014), including promiscuity to confuse paternity, directly attacking potential perpetrators (Ylönen and Horne 2002), avoiding infanticidal individuals, aggression, and territoriality (Elwood and Kennedy 1990; Palanza et al 1994; Agrell et al 1998), as well as early termination of pregnancy to reduce the potential damage (Bruce effect, Bruce 1959; Eccard et al 2017). Counterstrategies against infanticide come with a cost for the female, however, as these increase the risk of injury and energetic investments (Agrell et al 1998; Ylönen and Horne 2002).…”

Neurogenetics of Aggressive Behavior: Studies in Rodents

“…However, both male and female golden hamsters show a high level of aggression, with females usually dominating males (Payne and Swanson, 1970). Females of many rodent species show intense aggressive behavior during specific periods after giving birth, referred to as maternal aggression, this protects their newborn offspring from male intruders (Palanza et al, 1994). In most rodents, female aggressive behavior becomes more frequent shortly before gestation, reaches a peak at the first week postpartum, and declines thereafter (Noirot et al, 1975; Erskine et al, 1980).…”

Rodent mothers increase vigilance behaviour when facing infanticide risk

“…Rodent females can recognise previous mates 30 , and males are less likely to kill their own litter, due to familiarisation to the female around mating 31 . Our results suggest that females were able to assess the risk level of infanticide through male odours, and thus fine-tune their behaviour accordingly 32,33 (but see 34 ). This response capacity may allow females to optimize investment in current offspring protection, while saving time and energy to spend on alternative activities, e.g.…”