A comparison of social behaviour in two rodent species: implications for the mating system of mound‐building mice, Mus spicilegus

Abstract

Mound‐building mice, Mus spicilegus, and house mice, Mus musculus musculus, are closely related species, sympatric in northern Bulgaria. Many studies report a polygynous mating system in populations of M. m. musculus, but little is known about the mating system of M. spicilegus. Mus spicilegus displays some behavioural features of social monogamy, but the presence of monogamy has been questioned. To test whether M. spicilegus is monogamous, patterns of amicable and agonistic behaviour in M. spicilegus and M. m. musculus were studied in intraspecific male–male, female–female and male–female dyadic encounters. Results indicated that M. spicilegus displayed significantly less amicable, more defensive and more offensive behavioural events than M. m. musculus. The higher aggressiveness of M. spicilegus seems to be more compatible with a monogamous mating system than with a polygynous one.