Contents

Roost selection by barbastelle bats (Barbastella barbastellus, Chiroptera: Vespertilionidae) in beech woodlands of central Italy


Abstract


The barbastelle bat, Barbastella barbastellus (Schreber, 1774) is a medium-sized,
tree-dwelling vespertilionid classified as ?Endangered? in Italy; in western Europe
it may be one of the rarest bat species. B. barbastellus shows roosting preferences
that should be regarded as a key point in conservation protocols. We examined roost
selection in a breeding population of B. barbastellus from the Abruzzo Lazio and
Molise National Park (central Italy) at three levels: woodland structure and management
type; tree characteristics; and cavity characteristics.
In 2001-2002, we fitted 31 adult B. barbastellus (29 lactating females, one pregnant
female and one male) with 0.48g radio-tags and tracked them to their roost-trees.
The bats were tracked for 4.5 ± 3.7 days (range: 0-12 days). We located 33 roosts
used by 25 subjects (1.8±1.2 roosts/bat, range 1-5). The bats switched roosts frequently:
13 bats used more than one tree over the study period. A chi-square analysis
showed that the roosts were not distributed at random across woodland categories:
unmanaged woodland was positively selected, whereas shelterwood-harvested
woodland was used in proportion to its availability, and ?pastures+scattered trees?
was avoided.
Twenty out of 33 roost trees were dead Fagus sylvatica trees; conversely, living F.
sylvatica
dominated in a tree sample obtained at random; dead trees were used more
than expected (Χ² test, P <0.001). Overall, roost trees were significantly taller and
had a larger diameter at breast?s height and more cavities than random trees; they
also had a lower percent canopy closure than random trees. To highlight which
variables were actually associated with selection, we devised a logistic regression
model. The full model was significant (P <0.001); removal of tree type and tree
height affected the model significantly, but the other variables did not produce
detectable effects. The bats roosted under loose bark in 20 of 27 trees, i.e. more frequently than expected (Χ² test, P < 0.05). B. barbastellus preferred cavities at a greater
height (median roost height = 10.1 m, n = 22; median random cavity height =
4.5 m, n = 30; Mann-Whitney test, P < 0.01). Most roosts faced south (63.6% south
facing: 91-270 degrees; 36.4% north facing: 271-90 degrees, n = 22; Χ² test, P <
0.05). A logistic regression model including cavity type, height above ground and
direction faced was significant (P <0.01) and all variables were important for selection.
B. barbastellus is probably unable to find suitable roosting sites where intensive and
non-selective logging is conducted: areas of ancient woodland should be protected
to ensure optimal roosting conditions. In roosting areas, felling operations should
be avoided as far as possible; in logged areas, selective timber harvesting protocols
preserving dead trees and a significant fraction of mature trees should be adopted.
We are indebted to the Nando Peretti Foundation and the Parco Nazionale
d?Abruzzo Lazio e Molise for funding our work.

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NBN: http://nbn.depositolegale.it/urn%3Anbn%3Ait%3Aatit-7875

DOI: http://dx.doi.org/10.4404/hystrix-14.0-4273

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Hystrix, the Italian Journal of Mammalogy ISSN 1825-5272 (electronic version) 0394-1914 (printed version) Impact Factor (2016) 1.479, CiteScore (2016) 3.51.
Published by Associazione Teriologica Italiana
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