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Dietary composition, resource partitioning and trophic Niche Overlap in Three Forest Foliage-Gleaning bats in Central Europe

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Andreas M. , Reiter A. , Benda P.

Acta Chiropterologica

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2012

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tom 14

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nr 2

EN

A diverse syntopic bat community was studied in Central Europe. The study was primarily aimed at forest bats utilizing a foliage-gleaning foraging strategy (Myotis nattereri, M. bechsteinii and Plecotus auritus). The results indicated the foliage-gleaning foraging strategy and the effective resource partitioning. Once a certain diet item comprises an important food resource for one bat species, it is usually exploited much less by the other two bat species, and despite important seasonal dietary changes this pattern lasts throughout the entire season. Dietary composition varies more among the entire guild of forest foliage-gleaning bats than it does between these species and their morphological siblings or evolutionarily related species (e.g., Plecotus auritus vs. P. austriacus or Barbastella barbastellus, Myotis nattereri vs. M. emarginatus). The results are not fully consistent with the predictions of sensory ecology, which presume that bats with longer ears feed more frequently on prey that generates sound. The results do not support the hypothesis that rare bats exploit a narrower range of prey. The relatively rare M. bechsteinii has a wider trophic niche, whereas the more common P. auritus exploits a narrower range of prey. Comparison of dietary composition and morphological and echolocation parameters indicates that larger species feed on harder prey, species with longer ears are moth-eating specialists and species with a higher call intensity exploit small dipterans, probably in uncluttered habitats.

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Prey selection and seasonal diet changes in the western barbastelle bat (Barbastella barbastellus)

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Andreas M. , Reiter A. , Benda P.

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nr 1

EN

The objective of the study was to describe the diet composition of western barbastelle bat (Barbastella barbastellus), its seasonal changes and main factors determining trophic niche of the species. Barbastelle bat feeds predominantly on moths and has the narrowest trophic niche within the entire studied bat community. A comparison of the food supply and the diet composition showed selectivity for larger species of moths. An increasing of absolute abundance of preferred larger moths within summer is accompanied with narrowing of bat's trophic niche. This pattern corresponds well with the conclusions of optimal foraging theory. Larger moths are preferred even in a period of their low relative abundance within a peak of abundance of smaller species. There are no abrupt seasonal changes in the bat's diet within season, but the narrow pool of available food supply seems to determine the trophic niche breadth within low prey diversity periods in early spring and late autumn. The exception is a late autumn period; most probably due to a change in food supply are preferred larger moths replaced in the diet by smaller individuals. Most of the moths' species cease to fly and chiefly only smaller moth species are flying and attracted by UV light. Larger moths still occur at studied area at that time, but they display minimal flying activities and they are detected using vegetation beating and sweeping. Furthermore, syntopic motheating foliage gleaner (Plecotus auritus) still feeds on larger moths at that time. This may indicate that the change in the diet of B. barbastellus is a consequence of poor or absent gleaning abilities of this species, which is not able to pick up the prey from the surface as P. auritus. Different hunting strategies are probably efficient trophic niche partitioning mechanisms reducing interspecific competition between these syntopic moth eating bats.

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Foraging habitat, home-range size and diet of a Mediterranean bat species, Savi's pipistrelle

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Kipson M. , Salek M. , Lucan R. , Uhrin M. , Maxinova E. , Bartonicka T. , Andreas M. , Kipson K. , Pusic A. , Rnjak D. , Naďo L. , Horacek I.

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nr 2

EN

The Mediterranean is considered one of the richest biodiversity regions in Europe, and bats contribute to this species richness. Within the last two decades, certain bat species traditionally considered as representatives of the Mediterranean have spread northwards and colonized areas outside this region. In our study, we focused on ecological requirements of one of these bat species, the Savi's pipistrelle (Hypsugo savii). We used radio-telemetry and diet analysis to describe habitat use, home-range size and diet composition of reproductive females of Savi's pipistrelle in the traditional core of its distribution range in the Mediterranean region. Our results indicate that Savi's pipistrelle is able to fly long distances and utilize a wide range of habitats within its home-range, with affinities for particular habitats depending on its reproductive status. In particular, pregnant females favoured rocky pastures and forest areas, followed by meadows and riparian habitat, whereas the affinity for riparian habitat increased in lactating females, followed closely by meadows, forest and rocky pastures. The larger affinity for riparian habitats during lactation might indicate its importance for successful rearing of young, which could be influenced in the future by increasing droughts and water shortage in the Mediterranean region. Nevertheless, based on our radio-telemetry and diet analysis the species shows a high degree of flexibility, as an opportunistic forager that flies across large areas on a nightly basis, which may be a good predisposition for colonizing new areas.

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Alcathoe bat (Myotis alcathoe) in the Czech Republic: distributional status, roosting and feeding ecology

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Lucan R. K. , Andreas M. , Benda P. , Bartonicka T. , Brezinova T. , Hoffmannova A. , Hulova S. , Hulva P. , Neckarova J. , Reiter A. , Svacina T. , Salek M. , Horacek I.

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tom 11

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nr 1

EN

Between 2001 and 2008, we recorded Myotis alcathoe at nine sites within three distant areas in the Czech Republic. The species identification was confirmed with cyt b sequences and four distinct haplotypes were identified. All the localities exhibit surprisingly uniform habitat characteristics: (1) old full-grown oak-hornbeam forests, with (2) numerous large trees in advanced stages of decay are present, and (3) a very small to large water bodies and/or patches of riparian vegetation surrounded by the forest. Using radiotracking techniques, we discovered 27 day roosts of M. alcathoe, located mostly in big oak, birch and lime trees inside extensive forest stands. All roosts were fissures or small cavities in a tree trunk and in branches in the canopies, some 16 m above the ground. Bats preferred trees that were higher, had higher canopy and canopy basement and had larger diameter at breast height than other available trees. Roost trees were surrounded by lower trees with lower canopy basements than available trees. Roost trees were in a poorer condition than other available trees. Roosts were occupied by up to 83 individuals in July but usually single individuals were found in the roosts in September. In contrast to syntopic M. mystacinus and M. brandtii, M. alcathoe has never been found in an anthropogenic roost (except for a fissure in concrete electricity pole). Preliminary analysis of the diet showed that nematoceran flies were the most important prey item along with spiders, caddis flies, small moths and neuropterans. In the observed ecological characteristics, M. alcathoe markedly differs from other European species of the genus Myotis. Its restricted habitat requirements are perhaps responsible for an islet-like pattern of its distribution and suggest an essential conservation value of the habitats of its occurrence.