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Although the importance of cattle grazed pasture to foraging bats has already been well documented, the relative importance of cattle dung compared with the cattle themselves is largely unknown. This was investigated by comparing two adjacent fields: a current and a recent area of organic cattle-grazed pasture in England. The cattle were exchanged between fields during each of two separate observation periods in June and July 2005, one of eight evenings and the other of ten. Hand-held detectors were used to record time-expanded bat passes simultaneously from comparable positions within each field for 150 minutes after sunset. In addition, two separate observation periods (one of three evenings and the other of four) was used to investigate bat activity over and away from cattle within the same field. In general, bat activity was statistically greater within the field containing cattle than in the field without cattle (paired t-test, t21 = 3.97, P < 0.001). Within the field containing cattle, bat activity was greater over cows than away from them (paired t-test, t6 = 2.48, P < 0.05). It is therefore suggested that cattle, rather than dung are the primary attractant for foraging bats. Specifically, the difference in bat activity between the fields with and without cattle was statistically significant for Eptesicus serotinus (paired t-test, t21 = 4.14, P < 0.001), Pipistrellus pipistrellus (paired t-test, t21 = 3.23, P < 0.01) and Myotis (Dunn's test, Z = 2.99, P < 0.01) bats. Management recommendations include keeping cattle within bat foraging areas, minimizing the use of anthelminthic avermectin-based drugs for cattle, and maintaining woodland/trees within and around cattle-grazed pasture.
Most previous studies of the use bats make of their foraging areas have been concerned with general habitat preferences rather than with microhabitats. The present study focuses on microhabitat preference within three landscape features: linear landscape elements, ponds and rivers. The importance of linear landscape elements to bats was investigated by placing recording stations next to treelines, and others in adjacent open spaces approximately 35 m away. Most pipistrelle (Pipistrellus pipistrellus and P. pygmaeus) bat activity was recorded next to treelines and very little over open spaces. Bats used treelines for both commuting and foraging, but flew closer to treelines when commuting than when foraging. More insects were caught, and more pipistrelle feeding attempts were recorded close to treelines than further away. The relationship between the number and type of landscape elements leading to and surrounding ponds, and the use pipistrelle and Daubenton's (Myotis daubentonii) bats make of such ponds, was similarly investigated. Bats preferred to commute to ponds along woodland edges and streams, and not along hedgerows. More bat activity was recorded over ponds that had little overhanging and surrounding vegetation in comparison to ponds that had more, and over large wide ponds in comparison to small narrow ones. The extent to which pipistrelle and Daubenton's bats' use of river corridors extends beyond the water body was also investigated. Bat activity decreased with increasing distance from rivers, up to a distance of 70 m. River sites which were wooded on both sides attracted more bat activity for a longer duration than sites which had no trees on either side. Pipistrelles made use of the wider river corridor whereas Daubenton's bats restricted their activity almost exclusively to the water body.
The number of orientation, feeding and social calls emitted by pipistrelle batsPipistrellus pipistrellus Schreber, 1774 andP. pygmaeus Leach, 1825 was recorded throughout the night at eight different sites. Social calls were unaffected by weather variables, whereas orientation calls and feeding buzzes were both significantly affected by cloud and temperature conditions. The number of emissions of each call type was significantly different between sites, indicating that the bats used different sites for different activities. Significant positive correlations between all three combinations of call types occurred only during the middle of the night, corresponding with the nadir of flying insects. This suggests that bats were engaged in activities other than feeding at this time, such as territory protection or mate attraction.
Bats may be vulnerable to predation during evening emergence and morning return to their roosts. Early emergence increases the risk of exposure to raptorial birds, but emerging late confers a risk of missing the dusk peak of aerial insects. Here, both emergence and return activity was studied in detail at the same roosts for the first time. We investigated six maternity colonies of pipistrelle bats (Pipistrellus pipistrellus and P. pygmaeus) in NE Scotland and recorded light levels and time of emergence and return of the bats with respect to sunset and sunrise on the same nights. Parameters of return activity generally occurred at lower light intensities than those of emergence. Therefore, the interval between dawn return and sunrise was generally longer than that between sunset and dusk emergence. Emergence and return were equal in duration. Bats clustered more on emergence in comparison with return during pregnancy and lactation, whereas during postlactation this trend was reversed.
The lesser horseshoe bat (Rhinolophus hipposideros) is a widespread but rare bat in central and southern Europe, having undergone a dramatic population decline in the 1950s and 1960s. However, an internationally significant population has persisted in the United Kingdom, which now appears to be increasing. The present study extends previous radio-tracking studies on R. hipposideros to confirm and extend species-specific habitat management recommendations. It is also the first to radio-track adult males in lowland England. Thirteen lesser horseshoe bats (eight males and five females, from two maternity roosts) were radio-tracked within and around the National Trust Sherborne Park Estate, Gloucestershire (UK), between June and October 2003. A total of 2599 fixes were obtained from active bats, classified as emergence circling (2.7%), commuting (10.3%), foraging (85.2%) and return circling (1.8%). Although commuting bats were mainly recorded along the edges of fields near to hedgerows or woodlands, more open commuting routes were also identified. The longest of these (used by a single bat) was in excess of 200 m through long-established open parkland during the darkest period of the night. Shorter distances (typically 30–100 m) were also flown between mature parkland trees. It is also notable that, immediately after emergence, a significant number of bats tracked from both maternity roosts crossed low over an unlit narrow two-lane country road. Habitat selection, assessed using compositional analysis based on the radio-tracking data, identified a preference for woodland habitats above all others, particularly broadleaf woodland. Wet broadleaf woodland was used for foraging by five of the 13 tracked bats. Parkland, grazed grassland and un-grazed grassland were also selected. Arable land was the least selected. This is the first study in which compositional analysis has revealed a preference for grazed over un-grazed grassland. Grazed grassland was also selected above parkland (only some of which was grazed), suggesting that the presence of cattle may be more important than mature parkland trees. Low sample sizes prohibited the use of sex-specific compositional analyses. However, it was still notable that when comparing the sexes, females showed an increased preference for woodland and a decreased preference for grassland. It is apparent from the present study that lesser horseshoe bats are flexible in their use of foraging habitat. They are able to forage within habitats other than woodland (such as scrub and isolated trees), and cross open gaps to reach these areas. However, these foraging situations are likely to be sub-optimal. Landscape management around lesser horseshoe maternity colonies should focus on optimal foraging habitats. These comprise linear landscape elements (such as hedges, tree-lines, rivers and woodland edges), woodland, and grazed parkland containing mature trees. Additionally, future conservation studies should consider both sexes, due to the possibility that sex-specific differences in habitat use exist.
Close approach radio-tracking was used to investigate time and space use for both sexes of Rhinolophus hipposideros. Fifteen bats (nine males and six females, from three roosts) were radio-tracked (fi01_223.gif = 6.7 nights) within and around the National Trust Sherborne Park Estate, Gloucestershire (UK), between June and October 2003, at least seven of which (six males and one female) relocated to a different day roost after capture. The mean number of activity bouts per night was 3.5, each lasting for an average of 148 minutes. The mean distance travelled between fixes during each bout of activity was 3.8 km, and per night was 14.2 km. An average of 3.3 (SE = 1.8, range = 1–7, n = 12) night roosts were used per bat. Those individuals which continued roosting within the estate (n = 13) occupied a group foraging range covering approximately 1,175 ha with a 6.3 km range span (100% minimum convex polygon). The corresponding areas using the 95% Kernel isopleth and 95% Dirichlet tessellation enclosed approximately 539 ha and 1,553 ha, respectively. The maximum distance a bat was tracked from the roost of capture was 4.6 km, although the mean (n = 15) was much lower (2.2 km). A mean of 42% of the radio-tracking fixes from bats with at least one whole night of data were associated with night roosting, and of those, 56% were from the boiler room of a residential property within Sherborne village (used by 12 of the 15 bats). Therefore a range of suitable night roosts (i.e. sheltered locations adjacent to foraging areas) should be available throughout the foraging range (a minimum of 3 km from the roost) of a R. hipposideros colony. Night roosts on the edge of the home range, and warm night roosts are especially important.
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