Social networks of the greater horseshoe bat during the hibernation season: a landscape-scale case study

Abstract

Bats are highly social animals, and the interactions between individuals are likely to be important to their ecology and conservation. Social structures are affected by the physical environment (spatial factors), as well as varying over time and seasons (temporal factors). Compared with many other taxa, individual bats are capable of moving large distances, so experience a range of spatial locations. They have long life spans, providing opportunities to interact with others over a long period, and are often highly gregarious. Using a long-term data set, we examined the social behaviour, along with spatial and temporal influences, of greater horseshoe bats, Rhinolophus ferrumequinum , during hibernation using social network approaches. Across 17 years, 2808 individuals were monitored, yielding a total of 5952 records at 21 roost locations. We investigated how individuals’ life history traits (sex, age and breeding status of females) and the frequency of observation affected social associations and identified factors that influenced the movement of individuals between locations. Older and male animals were significantly more central in the social network, and adult males may act as a link between socially separate individuals within the society. The social network had high nonrandom dyadic structuring, with assortment by age stronger in females than males, and this was likely to be influenced by spatiotemporal factors. In general, higher weighted betweenness scores were recorded in a noncore hibernaculum, suggesting that these sites, despite low numbers of bats being present, may act as locations to connect less-connected individuals, as well as communities. Finally, movements between hibernacula were only associated with the frequency of observation rather than any life history trait. These results illustrate the interconnectivity across sites, stressing the need for appropriate cross-jurisdiction species management plans to be created for species that utilize and move between multiple sites within the landscape. • Older and male bats are more central in social networks during hibernation. • Assortment by age is stronger in female bats compared to males. • Assortment is likely to be influenced by spatiotemporal factors. • Movement between hibernation sites was only affected by frequency of observation.