Do bigger bats need more time to forage?

We test the hypothesis is that bats using the same area and at the same time would be using similar preys, but they would have different foraging times due to specific differences in biomass. A total of 730 captures was analyzed 13 species of Vespertilionidae and Molossidae bats netted over a small dam in southeastern Brazil from 1993 and 1999. The relationship between the average time of captures and the biomass of the species of Vespertilinidae and Molossidae most frequent (captures > 4) was positive and significant (r = 0.83, p = 0.022, N = 7). Two lines are discussed to answer the longer foraging time for bigger bats: 1) larger insectivorous bats don't consume proportionally larger preys and 2) larger insects are less available

Timing of the evening emergence from day roosts of the grey-headed flying fox, Pteropus poliocephalus: the effects of predation risk, foraging needs, and social context

This study addresses the functional question of how variation in foraging strategy, predation risk, and social context influence the timing of the evening emergence from day roosts of the grey-headed flying fox, Pteropus poliocephalus. The onset of evening emergence was expected to vary according to the relative costs and benefits of emerging early and should, therefore, reflect an optimal trade-off between predation risks and foraging needs. The onset of the colony-wide emergence was closely correlated with the time of sunset and cloud cover. However, as expected, the onset of the colony-wide emergence was delayed when a diurnal avian predator was present, whereas the onset was advanced during lactation when presumably energetic demands are higher. The trade-off between predation risks and foraging needs was further reflected in the emergence times of individual bats: adult females emerged earlier when they had higher foraging needs as indicated by their body condition; young emerged later when they were smaller and likely to be more at risk from predation due to their less developed flying skills. However, the emergence time of adult males depended on their social status: smaller bachelor males emerged from the colony earlier than larger harem-holding males who guard their harems until the last female had left. Thus, whereas the colony-wide emergence time reflected the outcome of a trade-off between predation risks and general foraging needs, on an individual level, the outcome of this trade-off depended on sex, age, body condition, and structural size and was modified by social context

Data from: Population genetic structure of serotine bats (Eptesicus serotinus) across Europe and implications for the potential spread of bat rabies (European bat lyssavirus EBLV-1)

Understanding of the movements of species at multiple scales is essential to appreciate patterns of population connectivity and in some cases, the potential for pathogen transmission. The serotine bat (Eptesicus serotinus) is a common and widely distributed species in Europe where it frequently harbours European bat lyssavirus type 1 (EBLV-1), a virus causing rabies and transmissible to humans. In the United Kingdom, it is rare, with a distribution restricted to south of the country and so far the virus has never been found there. We investigated the genetic structure and gene flow of E. serotinus across the England and continental Europe. Greater genetic structuring was found in England compared with continental Europe. Nuclear data suggest a single population on the continent, although further work with more intensive sampling is required to confirm this, while mitochondrial sequences indicate an east–west substructure. In contrast, three distinct populations were found in England using microsatellite markers, and mitochondrial diversity was very low. Evidence of nuclear admixture indicated strong male-mediated gene flow among populations. Differences in connectivity could contribute to the high viral prevalence on the continent in contrast with the United Kingdom. Although the English Channel was previously thought to restrict gene flow, our data indicate relatively frequent movement from the continent to England highlighting the potential for movement of EBLV-1 into the United Kingdom