Transcript Short report about bat migration at Måkläppen (Falsterbo) 2013

Short report about bat migration at Måkläppen (Falsterbo) 2013
Lothar Bach, Petra Bach, Sophie Ehnbom & Måns Karlsson
Introduction
Since 2007 we are running automated detector systems for bat migration studies on the
German East Frisian Islands (Bach et al. 2005, BACH et al. 2009, FREY et al. 2012). Out of
that experience and the fact that bats often use the same migration routes as birds in northern
Europe we tested whether it was possible to survey bat migration at Måkläppen., since
Falsterbo is known as a bird and bat migration point in southern Sweden (AHLÉN 1997,
KARLSSON 2004). We are using an automatical detector monitoring. Although we only could
check a short part of the migration period and that we know that bats cross the Öresund in
front of the Falsterbo Lighthouse, it turned out, that we got a good first picture about bat
migration (time and species) (BACH & BACH 2012, BACH et al. 2013). Therefore we are happy
to continue our studies in 2014.
Methods
The study was carried out from 22nd of April until 23th of September 2013. Like in 2010 and
2012 we used an AnaBatTM SD1 Bat detector (Titley Electronics, Australia) for the
automatical detector monitoring. The AnaBat system is a so called dividing system and we
used the dividing factor 8. The monitoring time was determined between sunset and sunrise.
Like in 2012 that we reloaded the battery with a solar and used a modem which allowed us to
download the data instantly. Because the system worked well over the whole study period we
only entered Måkläppen at the 17.9.2013 for installing and reinstalling the equipment and
once to check the system and refine the time for monitoring. In autumn we recognized a
problem with the modem, so the study ended at 23th of September. The equipment was
fetched on the 30th of October.
The positive part of the AnaBat system is, that it create small file sizes that makes it possible
to download data via mobile phone connection. The negative part of that system is that the
determination of the bat species is limited due to the dividing system. So in several cases bats
can only be determinate up to a genus or group level, such as Pipistrellus spec. or “Nyctaloid”
that contains not clearly determinable bats of the genus Nyctalus, Eptesicus and Vespertilio.
The detector was situated at the seamark at the outermost part of Måkläppen (see fig. 1).
Fig. 1: position of the AnaBat detector at the seamark (left), microphone with reflection mirror (middle) and
the solar panel (right).
Results and discussion
All together we recorded 2968 bat contacts of at least seven species and two genus (Myotis
and Plecotus), that cannot be determinated further with that detector system. Eptesicus
nilssonii (Nordisk fladdermus) was by far the most common bat recorded, followed by
Pipistrellus nathusii (Trollfladdermus) and Pipistrellus pygmaeus (Dvärgfladdermus). Most
astonishing was the low numbers of Nyctalus noctula (Store fladdermus), a typical migrating
bat species (tab. 1). In 18 cases a Vespertilio murinus (Gråskimlig fladdermus) and in 82 cases
a Pipistrellus pipistrellus (Pipistrell) was recorded. 111 bat contacts could only determined as
“Nyctaloid”, a species group that contains of the species of the genus Nyctalus, Eptesicus and
Vespertilio (see tab. 1).
Tab. 1: species composition and number of contacts 2013
scientific name
Swedish name
Number of
contacts
Nyctalus noctula
Stor fladdermus
94
Vespertilio murinus
Gråskimlig fladdermus
18
Eptesicus nilssonii
Nordisk fladdermus
1154
Eptesicus serotinus
Sydfladdermus
22
Pipistrellus pygmaeus
Dvärgfladdermus
474
Pipistrellus nathusii
Trollfladdermus
995
Pipistrellus pipistrellus
Pipistrell
82
Nyctaloid*
111
Pipistrellus spec.
1
Myotis spec.
13
Plecotus spec.
Långörad fladdermus
4
* = Group Nyctaloid: Nyctalus, Eptesicus, Vespertilio
In contrast to 2012 the bats did not use the island throughout the whole summer. Whereas bats
occur at Måkläppen frequently during 2012, they were not present there from mid of June to
end of July. However, Eptesicus nilssonii occurred out hunting at Måkläppen between mid of
May and end of July.
400
350
Pipistrell
Dvärgfladdermus
Langörad flöadermus
Myotis spec.
300
number of contacts
599
number of bats per species per night at Måkläppen 2013
(n = 2968)
Pipistrellus spec.
Trollfladdermus
250
Nyctaloid
S ydfladdermus
200
Nordisk fladdermus
Grå-skimlig fladdermus
S tor fladdermus
150
100
50
Figure 2: bat activity in 2013
23.9.13
16.9.13
9.9.13
2.9.13
26.8.13
19.8.13
12.8.13
5.8.13
29.7.13
22.7.13
15.7.13
8.7.13
1.7.13
24.6.13
17.6.13
10.6.13
3.6.13
27.5.13
20.5.13
13.5.13
6.5.13
29.4.13
22.4.13
0
While Pipistrellus nathusii, the main species of our interest, was rarely present on Måkläppen
during the breeding period, it appeared much more common and regular during migration,
especially during autumn migration. As in 2012 the migration of that species started around
mid of August and continued until at least end of the survey in mid of September.
The data show also that Pipistrellus pygmaeus, one of the most common bat species in
Falsterbo, was also mainly recorded during the migration period. Whether these animals were
migrating (see AHLÉN et al. 2009, MEYER 2010) or not cannot be answered here.
The results from all three investigated years show that bat migration (spring and autumn) take
place along Måkläppen. Although we know from own observation during the last 10 years at
Falsterbo that bats also leave the peninsula at other points the results show that the seamark is
a representing place to study bat migration with automated detector systems. Therefore we are
looking forward to collect important data about bat migration at Falsterbo during at least
2014.
Literature
AHLÉN, I. (1997): Migratory behaviour of bats at south Swedish coasts. - Zeitschrift für
Säugetierkunde, 62:375- 380.
AHLÉN, I., L. BACH and H. J. BAAGØE (2009): Behaviour of scandinavian bats during
migration and foraging at sea. - Journal of Mammalogie, 90(6): 1318-1323
BACH, L., C. MEYER-CORDS & P. BOYE (2005): Wanderkorridore für Fledermäuse. Naturschutz & Biologische Vielfalt 17: 59-69.
BACH, L., BACH, P., HELGE, A., MAATZ, K., SCHWARZ, V., TEUSCHER, M. & J.
ZÖLLER (2009): Fledermauszug auf Wangerooge - erste Ergebnisse aus dem Jahr
2008. – Natur- und Umweltschutz (Zeitschrift Mellumrat) 8(1): 10-12.
BACH, L. & P. BACH (2012): Report of a pilot project to study bat migration in Falsterbo. –
unpubl. report to Länstyrelsen Skane: 4 pp.
BACH, L. & P. BACH, S. Ehnbom & M. Karlsson (2013): Short report about bat migration at
Måkläppen (Falsterbo) 2012. – unpubl. report to Länstyrelsen Skane: 3 pp.
FREY, K., BACH, L., BACH, P. & H. BRUNKEN (2012): Fledermauszug entlang der
südlichen Nordseeküste. – Naturschutz & Biologische Vielfalt 128: 185-204.
KARLSSON, L. (2004): Wings over Falsterbo. - Report No. 222 from Falsterbo Bird
Observatory. Anser, Supplement 50. Wallin & Dalholm Boktryckeri AB. Lund: 180 S.
Dipl. Biol. Petra & Lothar Bach
Freilandforschung, zool. Gutachten
Hamfhofsweg 125 b, D-28357 Bremen, Germany
Phone: +49 (0)421-2768953
Email: [email protected] & [email protected]
Sophie Ehnbom och Måns Karlsson
Falsterbo Fågelstation
Fyrvägen 35, S-23940 Falsterbo
Phone: 040-470688
Email: [email protected] & [email protected]
Logg for visits at Måkläppen, Falsterbo 2013:
16 April
1415-1545
1,5 hours
Installing equipment (PB, SE)
17 May
1710-1815
65 min
Change of modem and memorycard (SE)
17 Sept
1325-1405
40 min
Change of monitoring time (SE)
1 Oct
30 Oct
1620-1710
1220-1320
30 min
1 hour
Battery change (SE)
Recovery of equipment (PB, SE)