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New frontiers in our understanding of Bechstein’s Bat in the UK
... As a result, in areas where the Bech stein's bat population is not increasing, most colonies will be situated in, or in close proximity to, forest patches that have historically been occupied. Previously, Bechstein's bats have been described as highly dependent on larger patches of old growth deciduous forest (Dietz and Pir, 2009;Becker and Encarnação, 2012;Barlow et al., 2013). We suggests that the historical continuity of forest patches may also be highly relevant to the current distribution of Bechstein's bats at a local scale, especially in areas where the population has not recently expanded. ...
... First, it is unbiased in terms of predictions regarding forest quality. Two roost sites (B and D) were situated in small isolated forest fragments (<6 ha), which would not have had a high priority as sampling site during summer surveys (e.g., Becker and Encarnação, 2012;Barlow et al., 2013). Second, it allowed for the discovery of two (presumed) summer maternity colonies located on private property that would not have been found during a summer survey due to restrictions in accessibility. ...
Bats display marked seasonality throughout the temperate zone and use different habitats during different parts of the year. Unfortunately, detailed information regarding seasonal distribution and movements is often lacking, thereby hampering the development of adequate conservation measures. In this study we used radio telemetry to track females of the endangered Bechstein's bat (Myotis bechsteinii) from autumn swarming sites to their summer maternity colony ranges. We were able to tag 22 individuals, 18 of which were subsequently recovered at nine roost sites up to 20.6 km away. Females from multiple colonies visited the same swarming site on a single night. Concurrently, we recovered females from a single maternity colony at different swarming sites on the same night. The catchment area of the investigated swarming sites measured 27.1 km2, and was skewed to the northwest. Tagged bats were recovered in forest fragments ranging in size from 5.42 to 128.98 ha. Notably, all but one of the recovered roosts were found in forests that have been continuously wooded since at least 1775. Surveys during the summer at these sites confirmed the presence of maternity colonies at six out of seven locations that could be investigated. Our study contributes to our understanding of swarming behavior and seasonal movement patterns, and exemplifies how these can be used to complete the year-round habitat use of bat species.
... The Sussex Autobat acoustic lure was developed in 2001 to improve capture rates for bats in British woodlands, and particularly for the elusive Bechstein's bat Myotis bechsteinii. Once the effectiveness of the technique had been demonstrated by field experiment and pilot surveys (Hill and Greenaway, 2005;2008) it was incorporated into a systematic survey, coordinated and run by the Bat Conservation Trust, which mapped the national distribution of Bechstein's bat in the UK (Miller, 2012;Barlow et al., 2013). ...
... Since these initial experiments, the lure has been developed further and used on a number of projects focussed on M. bechsteinii and other species; in Britain (e.g. Barlow et al., 2013;Miller, 2012;Murphy, 2012;Hill & Greenaway, 2006) and in Europe (Schöner, Schöner & Kerth, 2010;Goiti et al., 2007). ...
I investigate tools for studying bat species’ assemblages in woodlands, at varying spatial scales; including species distribution modelling (MaxEnt) for Myotis bechsteinii in Britain at a broad-scale, and an investigation into the use of an acoustic lure (the Sussex AutoBat) as a method for increasing capture rates of bats in woodlands at a local scale. M. bechsteinii is limited in its distribution due to unsuitable climatic and habitat conditions and new colonies are likely to be found in broad-leaf or mixed woodlands where there are relatively warm winters and low summer precipitation. Future work should focus on further delineating the range for M. bechsteinii using habitat suitability maps produced in this study; and further investigation into factors limiting its distribution, for example summer and winter diet. I also found that an acoustic lure is likely to be a valuable tool for monitoring bat species’ presence and assemblages in woodlands. Bat species were disproportionately responsive to different lure call playbacks, some playbacks being more generalist and others more species-specific in their ability to elicit a response. I therefore suggest that the lure be used as part of a carefully considered integrative approach to woodland monitoring, along with other methods. Lure call playbacks should be chosen on a case-by-case basis, to minimise bias and limit disturbance on bat species populations where possible. I conclude that it is important to use multi-scale tools to study bats, from the broad level of the species range, down to the fine scale of how they use specific habitats. Only then, can effective management guidelines and practices be put in place and habitats protected, to safeguard the future of bats in the landscape.
Reinstating forestry practices, such as coppicing, thinning the understorey and grazing, has become a key element of proposals for improving the conservation value of broadleaved woodlands in Europe. However, the consequences of such woodland management for bats are poorly understood because of a lack of knowledge concerning their habitat requirements. We studied the brown long‐eared bat Plecotus auritus in South East England to determine how their patterns of habitat use could inform conservation management. Radio‐tracking of 38 adult females showed that they foraged primarily in woodland and that each had a foraging area (mean = 4.4 ha) that they returned to on successive nights. Core foraging areas (mean = 2.1 ha) were characterized by more cover and greater species diversity in the understorey layer than more peripheral areas. Hedgerows were also used for foraging in the late summer and autumn. Most conservation activities for this species have focused on protecting roosts in houses and other buildings. While such protection is important for bat conservation, efforts should also be made to protect foraging habitats in woodlands by maintaining cover of native species in the understorey layer and hedgerows that provide connectivity between woodland patches. Common conservation management practices, such as reinstating coppicing or grazing in semi‐natural broadleaved woodlands, could be detrimental for P. auritus and other woodland bats. Their impact on bats should be tested experimentally before they are widely promoted as a woodland conservation strategy.
1. A field experiment was used to test the effectiveness of a synthesized bat call as an acoustic lure to attract bats into mist nets in woodlands in southeast England. The stimulus was modelled on a social call of the rare Bechstein's bat Myotis bechsteinii.
2. In the Test condition, when the synthesized call was played, 23 bats of four species were captured, including six Bechstein's bats. In the Control condition, when no calls were played, only one bat was caught.
3. The bat call synthesizer is an effective tool for increasing capture rates for bats. Used as part of a systematic survey programme, it has the potential to provide the first baseline data on the distribution of bats in British woodlands.
We investigated the population genetics of seven maternity roosts of Bechstein’s bats widely distributed across the south of England. Across all of the populations sampled, two mitochondrial DNA microsatellite loci were fixed for single haplotypes. Genetic diversity across eight nuclear microsatellite loci was similar in all seven populations, with a mean He of 0.727. However, six of the populations showed substantial homozygote excess, with F
IS estimates greater than zero, indicative of recent inbreeding. Bottleneck tests also implied that six of the populations have experienced recent declines. Genetic differentiation among the populations was low, with a mean intersite F
ST estimate of 0.041. There was no significant isolation by distance using allele frequency-based criteria (F
ST and genetic distances), however, a weak correlation was found using the allele size-based R
ST criterion. Assignment tests were unable to distinguish the seven sampling sites as distinct clusters. Mean intra-roost relatedness (r) was 0.079, indicative of recent inbreeding relative to German populations. All but one of the bats had one or more half or full siblings in its maternity roost. In addition, family relationships of individuals within a colony were significantly commoner than family relationships among four proximal roosts <8 km apart. The results are discussed in the context of conservation requirements for this rare British bat.
To explain coloniality in birds and bats, communal roosts have been hypothesized to serve as information centers where colony members transfer knowledge about their habitat. If information is exchanged about food, individuals with low hunting success benefit by following successful foragers to their profitable feeding sites. Colony members should therefore forage together regularly and move in pairs or groups among different feeding places. In 1996 and 1997, we used radio-telemetry to study the nightly habitat use of ten adult female Bechstein's bats (Myotis bechsteinii) living in one maternity colony. Over several nights, each bat revisited its own foraging area, although females regularly switched day-roosts at the same time. Most individual foraging areas showed no, or only little, overlap with each other. Distances between individual activity centers were negatively and significantly correlated with the degree of individual day-roost association. Genetic similarity among colony members, determined using seven nuclear microsatellites, was significantly positively correlated with the degree of overlap among individual areas. Five females were repeatedly radio-tracked at different seasons, months apart. Even between years, all bats maintained their individual hunting areas. Because females are very loyal to their individual foraging areas and these areas are typically substantial distances from each other, information transfer about feeding sites is unlikely to be the crucial factor promoting coloniality. Therefore, other benefits of sociality like cooperative breeding may cause communal roosting. Strong fidelity to individual foraging areas suggests the importance of familiarity with the local habitat, and profound site knowledge could be a crucial "resource", promoting female philopatry in Bechstein's bats.
Many temperate insectivorous bats show marked sexual segregation during the summer, but in spectacular, pre-hibernation swarming, gather at caves to mate. In many species, sexual segregation is probably due to a gradient in aerial insect availability that confines females to lower elevations, where high reproductive costs are met by an abundant and reliable food supply. In the hawking and trawling Myotis daubentonii, we show that alongside inter-sexual segregation, there is intra-male segregation and suggest that this results from the exclusion of most males from high-quality habitat. These apparently excluded males suffer reduced foraging efficiency and mating success relative to males that roost with the females in summer. Changes in resources and behaviour at the end of the summer lead to a change in strategy that gives all males a chance to mate during swarming, but this does not overcome the paternity advantage to males that spend the summer with the females.
The availability of detailed environmental data, together with inexpensive and powerful computers, has fueled a rapid increase in predictive modeling of species environmental requirements and geographic distributions. For some species, detailed presence/absence occurrence data are available, allowing the use of a variety of standard statistical techniques. However, absence data are not available for most species. In this paper, we introduce the use of the maximum entropy method (Maxent) for modeling species geographic distributions with presence-only data. Maxent is a general-purpose machine learning method with a simple and precise mathematical formulation, and it has a number of aspects that make it well-suited for species distribution modeling. In order to investigate the efficacy of the method, here we perform a continental-scale case study using two Neotropical mammals: a lowland species of sloth, Bradypus variegatus, and a small montane murid rodent, Microryzomys minutus. We compared Maxent predictions with those of a commonly used presence-only modeling method, the Genetic Algorithm for Rule-Set Prediction (GARP). We made predictions on 10 random subsets of the occurrence records for both species, and then used the remaining localities for testing. Both algorithms provided reasonable estimates of the species’ range, far superior to the shaded outline maps available in field guides. All models were significantly better than random in both binomial tests of omission and receiver operating characteristic (ROC) analyses. The area under the ROC curve (AUC) was almost always higher for Maxent, indicating better discrimination of suitable versus unsuitable areas for the species. The Maxent modeling approach can be used in its present form for many applications with presence-only datasets, and merits further research and development.
Bernwood Forest Bech-stein's Project – First year results summary Durrant Evidence of recent population bottlenecks and inbreeding in British popula-tions of Bechstein's bat, Myotis bechsteinii
- C Damant
- J Hodgkins
- C J Thorne
- T C Beebee
- F Greenaway
- D Hill
Damant, C, Hodgkins, J, & Thorne, T 2011 Bernwood Forest Bech-stein's Project – First year results summary Durrant, C J, Beebee, T J C, Greenaway, F, & Hill, D A 2009 Evidence of recent population bottlenecks and inbreeding in British popula-tions of Bechstein's bat, Myotis bechsteinii. Conservation Genetics 10: 489-496
Modelling, mapping & monitoring woodland bats Master of Science by Research thesis Effectiveness of an acoustic lure for surveying bats in British woodlands
- Gilmour
- S Prep Harris
- D Yalden
Gilmour, L in prep. Modelling, mapping & monitoring woodland bats. Master of Science by Research thesis, University of Bristol Harris, S, & Yalden, D W 2008 Mammals of the British Isles: Handbook. 4th edn. The Mammal Society, Southampton Hill, D A, & Greenaway, F 2005 Effectiveness of an acoustic lure for surveying bats in British woodlands. Mammal Review 35: 116-122
F 2006 Putting Bechstein's bat on the map
- D A Hill
Hill, D A, & Greenaway, F 2006 Putting Bechstein's bat on the map. Final Report to Mammals Trust UK, London Hill, D A, & Greenaway, F 2008 Conservation of bats in British wood-lands. British Wildlife 19: 161-169
Bernwood Forest Bechstein's Project -First year results summary
- C Damant
- J Hodgkins
- Thorne
Damant, C, Hodgkins, J, & Thorne, T 2011 Bernwood Forest Bechstein's Project -First year results summary
Putting Bechstein's bat on the map
- D A Hill
- Greenaway
Hill, D A, & Greenaway, F 2006 Putting Bechstein's bat on the map.
Final Report to Mammals Trust UK, London
A desk study to evaluate the habitat needs of Bechstein's bat across its UK range. Final report to People's Trust for Endangered Species
- D Merrett
Merrett, D 2012 A desk study to evaluate the habitat needs of Bechstein's bat across its UK range. Final report to People's Trust for
Endangered Species, London
Bechstein's Bat Survey: Final Report. Bat Conservation Trust
- H Miller
Miller, H 2012 Bechstein's Bat Survey: Final Report. Bat Conservation
Trust, London
Maximum entropy modelling of species geographic distributions
- S J Phillips
- R P Schapire
Phillips, S J, Anderson, R P, & Schapire, R E 2006 Maximum entropy
modelling of species geographic distributions. Ecological Modelling
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