Kin structure and roost fidelity in greater noctule bats

Roost fidelity is an important aspect of mammalian biology. Studying the mechanisms underlying philopatry can help us understand a species’ energetic requirements, ecological constraints and social organisation. Temperate bat species notably exhibit a comparatively high degree of female philopatry, resulting in maternity colonies segregated at the mitochondrial level. We focus on the greater noctule,Nyctalus lasiopterus, to study this behaviour in more depth. We make use of microsatellite data for 11 markers across 84 individuals residing in Maria Luisa Park in Seville, Spain. At the time of sampling, this urban park boasted the highest number of registered bats of this species, among which three social groups were observed to segregate spatially. We studied the distribution of pairs of individuals across filial relationship categories and relatedness estimates relative to the social group of each individual. This analysis was complemented by information on roost-use frequency among a subset of genotyped bats. We found no significant relationship between roost use and genetic distance, but there was evidence of higher group-sharing with increased levels of relatedness. Mother-daughter pairs shared the same group more often than expected, as did pairs of individuals of relatedness above 0.36. We discuss the implications of these results in terms of the behavioural ecology of temperate bats and for conservation efforts aimed at preserving them.