Social organization in the aboriginal house mouse,Mus spretus Lataste: behavioural mechanisms underlying the spatial dispersion of competitors

Abstract

Abstract. Because rodents behave cryptically and often have large home ranges, the role of social defence in determining their spatial dispersion in grassland remains an enigma. Individual dispersion and access to resources could be determined mainly by the aggressive exclusion of intruders from large territories by residents, or by the scattered distribution of resources and avoidance of dominant competitors occupying preferred sites. The ways in which predictions from these two hypotheses correspond to intra-sexual competitive behaviour within unfamiliar dyads of the mouse Mus spretus, recently captured from two grassland populations, were examined. A series of tests in enclosures examined (1) exploration by intruders given a choice between a resident's soiled sites versus clean sites, or between resident-soiled sites versus sites bearing their own odour, in the absence of the resident; (2) the response of an intruder on meeting either the resident or another mouse, in an adjacent clean tunnel; and (3) the response of a resident to an intruder compared with mice meeting in a clean enclosure. In both sexes, dyads quickly established dominance relationships through brief attacks and chases, and static defensive postures, rather than persistent pursuit and flight. Intruders were strongly attracted to a resident's nest and subsequently were more aggressive towards the resident than towards an opponent from an unfamiliar enclosure. There was less differentiation in competitive behaviour and more mutual fighting between residents and intruders than between mice in clean enclosures, with relative body weight being the most important factor determining competitive behaviour. The results were thus more consistent with competition for dominance over suitable sites than investment in fierce aggression to drive competitors away.

Aggression and commensalism in house mouse: a comparative study across Europe and the near east

“…The low levels of agonistic behavior in both females and males of M. spretus seem rather surprising, yet it fits very well with the finding of Hurst et al [1996] that dominance over suitable sites is more important than investment in fierce aggression to drive competitors away in this free-ranging species. In other words, while fighting for scattered food is profitable and yields essential gains, it is probably wiser to find one's own shelter than to risk injuries associated with driving other mice out from already occupied shelters.…”

The response to the social environment reveals sex-dependent behavioural syndromes in the Bosca’s newt (Lissotriton boscai)

“…Even territorial species of salamanders out of the breeding period may be attracted to conspecific chemical cues when the other choice is a substrate with no odour (Verrell and Davis 2003). Previous studies with vertebrates showing conspecific attraction have suggested that individuals might assess site quality through conspecific chemical cues (Hurst et al 1996;Luque-Larena et al 2001;Aragón et al 2006b). Fig.…”

Mus spretus (Rodentia: Muridae)

“…The sedentary nature of older males, at the start of reproduction, suggests territorial organization (Cassaing 1984;Cassaing and Croset 1985). Nevertheless, tests performed on captive animals show that Mus spretus does not fiercely attempt to exclude others from its territory, but suggest that mice establish a dominance relationship using stylized submission postures and are relatively tolerant (Hurst et al 1996). This behavior is quite different from that of resident M. musculus, which are highly intolerant and aggressive toward unfamiliar intruders, which readily take flight to avoid resident attacks .…”