Paul A. Racey

Feeding behaviour of captive brown long-eared bats, Plecotus auritus

Abstract This study examined the relative importance of gleaning and aerial prey capture in the feeding behaviour of captive long-eared bats, and the extent to which echolocation was used. Noctuid moths, which form an important part of the natural diet, were caught in free flight or gleaned from surfaces with equal frequency. Echolocation calls were produced in 89% of aerial prey capture attempts and in 29% of cases where prey was obtained by gleaning. Aerial captures were more successful when echolocation was used, but when gleaning, bats were more, successful when attempting captures without echolocation. Bats were attracted by the fluttering sounds of moths, and it is suggested that they locate prey on surfaces by passive listening.

The use by bats of habitat features in mixed farmland in Scotland

ABSTRACT 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 Daubentons (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 Daubentons 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 Daubentons bats restricted their activity almost exclusively to the water body.

Temporal and spatial differences in the emission of calls by pipistrelle batsPipistrellus pipistrellus andP. pygmaeus

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.

Recent advances in the study of bats

A light beam scanner unit includes a light beam generating unit for generating light beams at a fixed power, a polygon mirror for reflecting light beams generated from the light beam generating means toward a surface to be scanned, thereby scanning it, and a light beam power sensing unit for sensing light beam power for scanning a surface to be scanned with the polygon mirror. This light beam scanner unit further has a mirror contamination sensing unit for sensing contamination of the polygon mirror by comparing a sensing result obtained from the light beam power sensing unit when light beams are emitted by the light beam generating unit with a preset reference value.