Sexual Segregation and Flexible Mating Patterns in Temperate Bats

Abstract

Social structure evolves from a trade-off between the costs and benefits of group-living, which are in turn dependent upon the distribution of key resources such as food and shelter. Males and females, or juveniles and adults, may have different priorities when selecting habitat due to differences in physiological or behavioural imperatives, leading to complex patterns in group composition. We studied social structure and mating behaviour in the insectivorous bat Myotis daubentonii along an altitudinal gradient, combining field studies with molecular genetics. With increasing altitude the proportion of males in summer roosts increased and only males were present in the highest roosts. With increasing altitude environmental temperature decreased, nightly variation in temperature increased, and bat foraging activity decreased, supporting the hypothesis that the harsher, high elevation sites cannot support breeding females. We found that offspring in female-dominated lowland roosts had a very high probability of being fathered by bats caught during autumn swarming at hibernation sites, in contrast to those in intermediate roosts, which had a high probability of being fathered by males sharing the nursery roost with the females. Whilst females normally appear to exclude males from nursery colonies, for those in marginal habitats, one explanation for the presence of males is that the thermoregulatory benefits to the females may outweigh disadvantages, such as competition for food, and give some males an opportunity to increase their breeding success. We suggest that the environment, and its effects on resource distribution, thus determine social structure, which in turn determines the mating pattern that has evolved.

Roads and bats: a meta‐analysis and review of the evidence on vehicle collisions and barrier effects

“…Males may also be more susceptible to collisions if they are more likely to roost or forage in the vicinity of roads: in many species, there is sexual segregation during the breeding season, and some evidence suggests that female bats occupy better quality habitats (Angell et al. ) or less fragmented habitat (Lintott et al. ) during this period.…”

Genetic connectivity among swarming sites in the wide ranging and recently declining little brown bat (Myotis lucifugus)

“…; Angell et al. ), further work would be required to assess the importance of mating activities occurring away from swarming sites to the overall mating strategies and contributions to gene flow in M. lucifugus . In a study of M. nattereri , Rivers et al.…”

Continental‐scale, seasonal movements of a heterothermic migratory tree bat

“…Unlike migratory birds that must feed throughout the winter to survive, all species of migratory tree bats are heterothermic endotherms capable of extended periods of deep, facultative, energy-saving torpor in response to unfavorable conditions, such as low air temperatures and lack of insect prey (Barbour and Davis 1969, Genoud 1993, McGuire and Guglielmo 2009; several species of tree bats are known or suspected to hibernate after migrating to their wintering grounds (Davis 1970a, Baker 1978, Mormann and Robbins 2007, Dietz et al 2009, Perry et al 2010. Additional distinctive natural history characteristics of most temperate-zone bats, such as ubiquitous autumn/winter mating and disparate distributions and behaviors of the sexes during spring through early summer (Racey 1982, Senior et al 2005, Weller et al 2009, van Toor et al 2011, Angell et al 2013, make it likely that migration behaviors of bats evolved in ways that could differ dramatically from those of many other types of migratory animals (Fleming and Eby 2003). Recent studies of migratory tree bats have revealed intriguing evidence that they migrate differently than birds and perhaps other bats, such as feeding en route rather than strictly during stopovers to supplement endogenous energy stores, and using a torpor-assisted migration strategy (McGuire et al 2011, Voigt et al 2012b.…”