Intra- and interspecific competition in western barbastelle bats (Bbastell bastellus, SCHREBER 1774): Niche differentiation in a specialised bat species, revealed via radio-tracking. Dissertation zur Erlangung des Grades "Doktor der Naturwissenschaften" am Fachbereich Biologie der Johannes Gutenberg-Universität in Mainz Jessica Hillen geb. am 09.01.1981 in Zell (Mosel) Mainz, 2011 Tag der mündlichen Prüfung: 16.12.2011 Western barbastelle bats in their tree roost. Background: View of the brook valley 'Ahringsbachtal'. Contents Contents. Abstract..............................................................................................................................................5 General introduction. ..........................................................................................................................7 Chapter I. Spatial organisation and foraging site fidelity of a population of female western barbastelle bats...................................................................................................................................................12 Abstract....................................................................................................................................13 1. Introduction. ....................................................................................................................14 2. Materials and methods......................................................................................................16 3. Results. ............................................................................................................................21 4. Discussion........................................................................................................................26 Acknowledgements. .................................................................................................................28 Chapter II. Interannual fidelity to roosting habitat and flight paths by female western barbastelle bats .........................................................................................................................................................29 Abstract....................................................................................................................................30 1. Introduction. ....................................................................................................................31 2. Materials and methods......................................................................................................33 3. Results. ............................................................................................................................37 4. Discussion........................................................................................................................45 Acknowledgements. .................................................................................................................47 Chapter III. Sex-specific habitat selection in an edge habitat specialist, the western barbastelle bat .........................................................................................................................................................48 Abstract....................................................................................................................................49 1. Introduction. ....................................................................................................................50 2. Materials and methods......................................................................................................52 3. Results. ............................................................................................................................55 4. Discussion........................................................................................................................61 Acknowledgements. .................................................................................................................64 Chapter IV. Resource partitioning in three syntopic forest-dwelling bat species .........................................................................................................................................................65 Abstract....................................................................................................................................66 1. Introduction. ....................................................................................................................67 2. Materials and methods......................................................................................................69 3. Results. ............................................................................................................................72 4. Discussion........................................................................................................................82 Acknowledgements. .................................................................................................................84 References........................................................................................................................................85 Personal grants to J. Hillen and additional funding. ...........................................................................98 Appendix..........................................................................................................................................99 Zusammenfassung. .........................................................................................................................104 Danksagung....................................................................................................................................106 4 Abstract Abstract. In the present thesis I examined individual and sex-specific habitat use and site fidelity in the western barbastelle bat, Barbastella barbastellus, using data from a four-year monitoring in a Special Area of Conservation in Rhineland-Palatinate, Germany. The western barbastelle occurs in central and southern Europe from Portugal to the Caucasus, but is considered to be rare in large parts of its range. Up to now, long-term field studies to assess interannual site fidelity and the possible effects of intra- and interspecific competition have not been studied in this species. Nevertheless, such data provide important details to estimate the specific spatial requirements of its populations, which in turn can be incorporated in extended conservation actions. I used radio-telemetry, home range analyses und automated ultrasound detection to assess the relation between landscape elements and western barbastelle bats and their roosts. In addition, I estimated the degree of interspecific niche overlap with two selected forest- dwelling bat species, Bechstein's bat (Myotis bechsteinii) and the brown long-eared bat (Plecotus auritus). Intra- and interannual home range overlap analyses of female B. barbastellus revealed that fidelity to individual foraging grounds, i.e. a traditional use of particular sites, seems to effect the spatial distribution of home ranges more than intraspecific competition among communally roosting females. The results of a joint analysis of annual maternity roost selection and flight activities along commuting corridors highlight the necessity to protect roost complexes in conjunction with commuting corridors. Using radio-tracking data and an Euclidean distance approach I quantified the sex-specific and individual habitat use by female and male western barbastelle bats within their home ranges. My data indicated a partial sexual segregation in summer habitats. Females were found in deciduous forest patches and preferably foraged along linear elements within the forest. Males foraged closer to forest edges and in open habitats. 5 Abstract Finally, I examined the resource partitioning between the western barbastelle bat and two syntopic bat species with a potential for interspecific competition due to similarities in foraging strategies, prey selection and roost preferences. Simultaneous radio-tracking of mixed-species pairs revealed a partial spatial separation of the three syntopic bat species along a gradient from the forest to edge habitats and open landscape. Long-eared bats were found close to open habitats which were avoided by the other two species. B. barbastellus preferred linear landscape elements (edge habitats) and forests, M. bechsteinii also preferred forest habitats. Only little overlap in terms of roost structure and tree species selection was found. 6 Introduction General introduction. Bat communities are unique in terms of species richness, niche diversity and life history characteristics, which are unusual for mammals of small body size (Kunz & Fenton, 2003). Compared to other mammals, bats show a pronounced seasonality, with specific requirements on each of their seasonal habitats: summer (maternity and male) roosts, mating places and hibernacula (temperate-zone species). The majority of the known bat species needs a set of suitable roosts embedded in a matrix of a variety of habitat patches that provide high quality food resources for at least the reproductive period. Most bat species forage close to each other on the same food resource, flying, and non-flying insects. This requires resource partitioning in one or more niche dimensions: foraging time, foraging habitat and prey type. Numerous field studies on the home range sizes, flight