July 31, during which females give birth and feed their offspring; second, in the
period between August 15 and September 31, during which young are flying and
individuals are expected to be less dependent on their reproductive roost. Habitat
characteristics were analysed in a radius of 100 m around the sampled point, using
a detailed habitat classification (Kerbiriou et al. 2010). Species calls were identified
through spectrogram analyses.
At large scale, we found that activity of common bats in railway verges was of
the same order of magnitude as in other habitats, except for aquatic habitats, which
are known as key habitats for numerous European bat species (Russo and Jones
2003; Nicholls and Racey 2006). Furthermore, we found that activity was even
greater in railway verges than in some other habitats for two aerial species:
N. leislerii and P. pipistrellus. For P. pipistrellus, a very generalist species
(Russ and Montgomery 2002), activity in railway verges was greater than in seven
other habitats. Overall, bat activity among railway verges was not inferior to the
activity in highly modified habitats such as continuous artificial surfaces, discontinuous artificial surfaces and arable land (confirmed for 4 of the 5 taxa studied).
At local scale, we found a negative effect of railway areas on the Myotis spp. for
the two sample periods and a positive effect on Nyctalus spp. for the
post-reproductive period. When focusing the analysis on the site type, we detected
few obvious significant differences in bat activity between the verges of railways
and the three other site types (field verges, plain field and plain wood). The significant difference for Nyctalus spp. during the post-reproductive period (lower
activity in woods than on railway verges) may seem contradictory with the positive
effect of surrounding areas of wood for these species at the same period. The
foraging ecology of these aerial hawking bats and their habitat requirements could
explain these results: Nyctalus spp. are species that forage mainly along edges, thus
more in forest verges than in the heart of forests, but otherwise inhabit the interior of
the forests, thus the amount of woodland habitat at the landscape level would have
also an overall positive effect.
It must be noted that except for the Myotis spp. group in the reproductive period,
we detected no difference between the verges of railways and those of fields. This
result seems to indicate a similar functioning role for railway verges on bats as that
of other linear verges, particularly on common aerial hawking bats (Verboom and
Huitema 1997).
Our results suggest that the presence of railway verges does not influence significantly the foraging/commuting activity of common bats, except for species like those
from the Myotis group, a group including mostly gleaner species, less generalist species
(Dietz et al. 2007) and some threatened species (Temple and Terry 2009).
In several cases (for P. pipistrellus at global scale and for Nyctalus spp. at local
scale), railway verges even seem to provide a significant habitat in intensive
agricultural landscapes where semi-natural elements, in particular linear elements
like hedgerows, tend to disappear. Railways, along with other artificial linear
infrastructures, may thus contribute to maintaining common bat populations in such
landscapes.
16 Ecological Roles of Railway Verges in Anthropogenic Landscapes …
265
period between August 15 and September 31, during which young are flying and
individuals are expected to be less dependent on their reproductive roost. Habitat
characteristics were analysed in a radius of 100 m around the sampled point, using
a detailed habitat classification (Kerbiriou et al. 2010). Species calls were identified
through spectrogram analyses.
At large scale, we found that activity of common bats in railway verges was of
the same order of magnitude as in other habitats, except for aquatic habitats, which
are known as key habitats for numerous European bat species (Russo and Jones
2003; Nicholls and Racey 2006). Furthermore, we found that activity was even
greater in railway verges than in some other habitats for two aerial species:
N. leislerii and P. pipistrellus. For P. pipistrellus, a very generalist species
(Russ and Montgomery 2002), activity in railway verges was greater than in seven
other habitats. Overall, bat activity among railway verges was not inferior to the
activity in highly modified habitats such as continuous artificial surfaces, discontinuous artificial surfaces and arable land (confirmed for 4 of the 5 taxa studied).
At local scale, we found a negative effect of railway areas on the Myotis spp. for
the two sample periods and a positive effect on Nyctalus spp. for the
post-reproductive period. When focusing the analysis on the site type, we detected
few obvious significant differences in bat activity between the verges of railways
and the three other site types (field verges, plain field and plain wood). The significant difference for Nyctalus spp. during the post-reproductive period (lower
activity in woods than on railway verges) may seem contradictory with the positive
effect of surrounding areas of wood for these species at the same period. The
foraging ecology of these aerial hawking bats and their habitat requirements could
explain these results: Nyctalus spp. are species that forage mainly along edges, thus
more in forest verges than in the heart of forests, but otherwise inhabit the interior of
the forests, thus the amount of woodland habitat at the landscape level would have
also an overall positive effect.
It must be noted that except for the Myotis spp. group in the reproductive period,
we detected no difference between the verges of railways and those of fields. This
result seems to indicate a similar functioning role for railway verges on bats as that
of other linear verges, particularly on common aerial hawking bats (Verboom and
Huitema 1997).
Our results suggest that the presence of railway verges does not influence significantly the foraging/commuting activity of common bats, except for species like those
from the Myotis group, a group including mostly gleaner species, less generalist species
(Dietz et al. 2007) and some threatened species (Temple and Terry 2009).
In several cases (for P. pipistrellus at global scale and for Nyctalus spp. at local
scale), railway verges even seem to provide a significant habitat in intensive
agricultural landscapes where semi-natural elements, in particular linear elements
like hedgerows, tend to disappear. Railways, along with other artificial linear
infrastructures, may thus contribute to maintaining common bat populations in such
landscapes.
16 Ecological Roles of Railway Verges in Anthropogenic Landscapes …
265