Search

Organisms sharing the same habitats may differ in small-scale microhabitat requirements or benefit from different management. In this study, set in Italy, we focused on two species of high conservation value, the cerambycid beetle R osalia alpina and the bat B arbastella barbastellus, which often share the same forest areas and in several cases the same individual trees. We compared the potential distribution and, at two spatial scales, the niches between such species. The predicted distributions largely overlapped between the beetle and the bat. The niches proved to be similar on a broad scale, yet not on the plot one. Compared with B . barbastellus, R . alpina tends to occur at lower altitude in more irradiated sites with lower canopy closure and uses shorter trees with wider diameters. B . barbastellus occurred more often in trees within forest or along its edges, whereas R . alpina lays eggs in trees found in clearings. B . barbastellus plots were more frequent in forest, R . alpina plots in forested pasture and open-shredded forest. Overall, exposure to sun influenced more critically site and tree selection by R . alpina, as a warm microclimate is essential for larval development. Although B . barbastellus reproduction may be favored by warmer roosting conditions, bats may also find such conditions in dense forest and in strongly irradiated cavities high up in tall trees that project above the canopy. We emphasize that subtle differences in the ecological requirements of syntopic taxa could be missed at broad scales, so multiple-scale assessment is always advisable. [ABSTRACT FROM AUTHOR]

Resource exploitation and competition for food are important selective pressures in animal evolution. A number of recent investigations have focused on linkages between diversification, trophic morphology and diet in bats, partly because their roosting habits mean that for many bat species diet can be quantified relatively easily through faecal analysis. Dietary analysis in mammals is otherwise invasive, complicated, time consuming and expensive. Here we present evidence from insectivorous bats that analysis of three-dimensional (3- D) textures of tooth microwear using International Organization for Standardization ( ISO) roughness parameters derived from sub-micron surface data provides an additional, powerful tool for investigation of trophic resource exploitation in mammals. Our approach, like scale-sensitive fractal analysis, offers considerable advantages over two-dimensional (2- D) methods of microwear analysis, including improvements in robustness, repeatability and comparability of studies. Our results constitute the first analysis of microwear textures in carnivorous mammals based on ISO roughness parameters. They demonstrate that the method is capable of dietary discrimination, even between cryptic species with subtly different diets within trophic guilds, and even when sample sizes are small. We find significant differences in microwear textures between insectivore species whose diet contains different proportions of 'hard' prey (such as beetles) and 'soft' prey (such as moths), and multivariate analyses are able to distinguish between species with different diets based solely on their tooth microwear textures. Our results show that, compared with previous 2- D analyses of microwear in bats, ISO roughness parameters provide a much more sophisticated characterization of the nature of microwear surfaces and can yield more robust and subtle dietary discrimination. ISO-based textural analysis of tooth microwear thus has a useful role to play, complementing existing approaches, in trophic analysis of mammals, both extant and extinct. [ABSTRACT FROM AUTHOR]

A naturally functioning riparian zone is essential for the ecological health of a river, filtering pollutants, supplying organic matter and providing a structural habitat for wildlife. Most lowland rivers would also naturally flood the riparian zone at regular intervals, thereby providing direct inputs of nutrients and water that create additional habitats and breeding opportunities for riverine species. We examined the relationship between the quality of the riparian habitat and foraging and activity of bats (Chiroptera), which are good indicators of ecosystem health. Twenty paired sites in the Rivers Lee and Colne catchments in England were selected to test the hypothesis that degradation in the quality of riparian habitat reduces foraging and activity in bats; paired sites were similar in terms of size, flow rate and water chemistry but differed in the quality of their riparian zones. AnaBat detectors were used to measure bat activity from 30 min before dusk to 30 min after sunrise on the same night at paired sites because recording frequency-divided bat echolocation calls in real time allows large amounts of data to be collected over long time periods in a digitized format. Significantly more feeding buzzes were recorded in sites with better quality riparian zones; no differences in overall bat activity were found between the two habitat types. Pipistrellus pipistrellus and Pipistrellus pygmaeus accounted for 96% of bat passes. Pipistrellus pygmaeus was significantly more active in high quality sites than P. pipistrellus; there was no difference between the two species in poor quality sites. We show that the quality of riparian buffer zones is important for the activity and feeding behaviour of pipistrelle bats. [ABSTRACT FROM AUTHOR]

Sex-biased behaviours are expected to play an important role in partitioning genetic variance in animal populations. Comparing genetic structure at markers with different modes of inheritance provides a means of detecting these behaviours and their consequences for population genetic structure. In colonially breeding mammals, the common combination of female philopatry and male vagility can promote contrasting patterns of genetic differentiation between the sexes, both via their effects on recurrent gene flow and on colonization. We examined sex differences in gene flow and structure by comparing maternally inherited mitochondrial DNA (mtDNA) and biparentally inherited autosomal loci in the Formosan lesser horseshoe bat Rhinolophus monoceros. We found that genetic partitioning was higher at mtDNA than autosomal markers in both sexes, indicative of female-biased philopatry and male-biased dispersal. Across Taiwan, isolation-by-distance was detected for all sex/marker combinations but was steeper for mtDNA than for nuclear markers. We suggest that isolation-by-distance shown from mtDNA at large scales is likely to reflect the stepwise founding of new breeding colonies by females during colonization. In contrast, no isolation-by-distance was found at smaller distances of up to 100 km, indicating that gene flow and/or recent shared ancestry homogenises genetic structure among nearby sites. Our results highlight the value of an indirect genetic approach to understanding sex-biased behaviours and their consequences in a little-studied species. [ABSTRACT FROM AUTHOR]

From 2001 to 2003 we radio tracked 23 Pipistrellus pipistrellus and 23 Pipistrellus pygmaeus to investigate whether there are any differences in foraging behaviour between the two cryptic species during the summer, and to consider whether any differences between these species are important for their conservation planning. There were significant differences between the two species in relation to flying time, mean maximum distances travelled from the roost, numbers of foraging bouts made and span of home ranges. The results suggest that P. pipistrellus makes more flights to a greater number of foraging locations (and possibly) feeding habitats than P. pygmaeus, although these foraging areas are likely to be closer to the roosts. This behaviour is particularly marked during lactation. In contrast, P. pygmaeus spends less time flying, makes fewer foraging bouts but travels further distances, suggesting that this species is selecting specific foraging habitats. These differences in foraging behaviour support the hypothesis that these species occupy different ecological niches, and conservation planners should be aware of these differences when considering the requirements of pipistrelles in the UK. [ABSTRACT FROM AUTHOR]