Relatedness, parentage, and philopatry within a Natterer's bat ( Myotis nattereri ) maternity colony

A conceptual framework to predict social information use based on food ephemerality and individual resource requirements

Environmental variability poses a range of challenges to foraging animals trying to meet their energetic needs. Where food patches are unpredictable but shareable, animals can use social information to locate patches more efficiently or reliably. However, resource unpredictability can be heterogeneous and complex. The behavioural strategies animals employ to exploit such resources also vary, particularly if, when, and where animals use available social information. We reviewed the literature on social information use by foraging animals and developed a novel framework that integrates four elements - (1) food resource persistence; (2) the relative value of social information use; (3) behavioural context (opportunistic or coordinated); and (4) location of social information use - to predict and characterize four strategies of social information use - (1) local enhancement; (2) group facilitation; (3) following; and (4) recruitment. We validated our framework by systematically reviewing the growing empirical literature on social foraging in bats, an ideal model taxon because they exhibit extreme diversity in ecological niche and experience low predation risk while foraging but function at high energy expenditures, which selects for efficient foraging behaviours. Our framework's predictions agreed with the observed natural behaviour of bats and identified key knowledge gaps for future studies. Recent advancements in technology, methods, and analysis will facilitate additional studies in bats and other taxa to further test the framework and our conception of the ecological and evolutionary forces driving social information use. Understanding the links between food distribution, social information use, and foraging behaviour will help elucidate social interactions, group structure, and the evolution of sociality for species across the animal kingdom.

Population structure, gene flow and relatedness of Natterer’s bats in Northern England

There have been significant declines in population numbers of many bat species in the United Kingdom, including Natterer’s batsMyotis nattereri, over the last century, largely due to anthropogenic changes. The philopatry, which temperate-zone bats often exhibit to their natal landscapes, in combination with anthropogenic threats, can lead to fragmentation, isolation and sub-division of populations. This may result in bottlenecks and declines in genetic diversity. Multi-scaled research is required to disentangle how the variation in the physical traits of bat species (e.g. affecting flight), as well as their social and behavioural traits (e.g. community size, migration, breeding systems), may affect the genetic health of populations and provide a potential buffer against fragmentation. We used microsatellite markers to characterise the genetic diversity and population structure present in Natterer’s bat colonies to determine whether summer roosting bat colonies were spatially differentiated or part of a meta-population. Analyses of population structure and measures of genetic relatedness suggest spatially differentiated populations of bats exhibit long term site fidelity to summer roosting sites, whilst high genetic diversity at sites indicates gene exchange occurs via swarming sites. Natterer’s bats in northern England may travel greater distances to swarming sites than has been previously documented.