DOI: 10.5061/dryad.qnk98sfd4
title: Movement paths of common noctule bats in the Berlin metropolitan area

description:   Cities are a challenging habitat for obligate nocturnal mammals
 because of the ubiquitous use of artificial light at night (ALAN). How
 nocturnal animals move in an urban landscape, particularly in response to
 ALAN is largely unknown. We studied the movement responses, foraging and
 commuting, of common noctules (Nyctalus noctula) to urban landscape
 features in general and ALAN in particular. We equipped 20 bats
 with miniaturized GPS loggers in the Berlin metropolitan area and related
 spatial positions of bats to anthropogenic and natural landscape features
 and levels of ALAN. Common noctules foraged close to ALAN only
 next to bodies of water or well vegetated areas, probably to exploit
 swarms of insects lured by street lights. In contrast, they avoided
 illuminated roads, irrespective of vegetation cover nearby. Predictive
 maps identified most of the metropolitan area as non-favoured by this
 species because of high levels of impervious surfaces and ALAN. Dark
 corridors were used by common noctules for commuting and thus likely
 improved the permeability of the city landscape. We conclude that
 the spatial use of common noctules, previously considered to be more
 tolerant to light than other bats, is largely constrained by ALAN. Our
 study is the first individual-based GPS tracking study to show sensitive
 responses of nocturnal wildlife to light pollution. Approaches to protect
 urban biodiversity need to include ALAN to safeguard the larger network of
 dark habitats for bats and other nocturnal species in cities.
description: The study area was located in the district of Marzahn-Hellersdorf
 in northeast Berlin and consisted largely of residential and commercial
 areas, with a high proportion of large pre-fab buildings in the north,
 gradually outnumbered by smaller houses in the south (Umweltatlas Berlin
 2010).  All work was conducted under the animal care
 and ethics approval of the federal agency (C113-G0114/15) and the approval
 of the conservation agency (IE 224-OA-AS/G/1167.2). Between June and early
 September 2015 and between July and August in 2016 and 2017, we captured
 20 male common noctule bats at natural and artificial daytime roosts in
 the parks ‘Parkfriedhof Marzahn’ and ‘Schlosspark Biesdorf’, two larger
 parks which are not or only partly illuminated by street lamps,
 respectively.  We attached a single GPS logger (Robin,
 CellGuide Ltd., Tel Aviv, Israel; Vesper, ASD technologies inc., Haifa,
 Israel) to the back of each captured bat using medical latex glue (Sauer
 Hautkleber, Manfred Sauer Germany). In 2016 and 2017, we added a small VHF
 transmitter (Telemetrie Dessau, Germany) to each GPS logger to improve the
 relocation of bats and tags. GPS locations were recorded every 30 seconds
 from 30 minutes before sunset until dawn. The earliest starting time was
 18:33 CEST (mean = 20:18 CEST) and the latest ending time was 2:46 CEST
 (mean = 23:07 CEST). We ignored GPS locations with extremely large
 (&gt; 1,000 meter) horizontal or vertical positional errors from
 further analysis. For a first inspection, we visualised the individual
 flight paths in QGIS 2.14 (QGIS Development Team, 2017) and removed
 locations from bats resting in a roost. We interpreted large gaps
 (&gt; 3min) in the recording of GPS locations as roosting, as the GPS
 signals were not received when bats stayed inside roosts. GPS locations
 were split into one or more trips per animal. We defined one trip as
 comprising the movement path between subsequent roosting events (as
 defined above). In the rare case of battery or signal failure during a
 trip, we still used the partly recorded trip in our analysis.