Bat migration routes

Project title: Identifying bat migration routes and corridors


  • Phenology: analysis of approx. 70,000 observations
  • Acoustic transect: measurements at twelve locations in spring and autumn
  • Telemetry: do bats migrate along migration routes and do they choose specific landscape features?


PAN Planungsbüro für angewandten Naturschutz GmbH
Rosenkavalierplatz 8
81925 Munich
Dr. Angelika Meschede
Tel.: +49 89 1228569-0



FKZ 3512 86 0200
Departmental Research Plan 2012
Term: 01.08.2012 – 30.09.2015

Wind turbines present a potential threat to migrating bats. However, there is very little known about their migration routes, so these cannot be taken into account when planning wind turbines. This pilot study assesses the available data on the seasonal occurrence of bats, evaluates research methods for studying migration and supplies results from field studies of the Noctule bat and Nathusius' pipistrelle. The project has already been completed. It was not possible to verify specific migration corridors within the scope of this study.

Bats migrate over long distances and can run into danger from wind turbines along the way. This research project therefore investigates the migratory behaviour of bats from the following angles:

  • Do migratory bats use migration routes and/or roosting areas and can these be identified?
  • Do they prefer specific landscape structures such as e.g. river valleys, mountain ridges or slopes and are these structures concentration points?
  • Is it possible to derive migration models and statements on the nature of the migration for the three species common noctule, lesser noctule and Nathusius' pipistrelle, and what differences if any are there between the species?


In the phenological analyses, the spatial and temporal distribution of the four species that migrate long distances were strikingly illustrated over an area of approx. 1,000 km (Germany, Switzerland and Austria) through the course of the year. The area represents a significant proportion of the Central European migration area. Almost 70,000 observations at almost 20,000 locations were compiled from literature, the bat coordination centre's data bases, natural history museums, ringing stations, nature conservation authorities and organisations, the Swiss Bat Conservation Foundation (Schweizer Stiftung Fledermausschutz) and other experts, and analysed and entered into the UTM grid maps in ten day periods.

The project team used an acoustic transect along the ridge of the Thuringian Forest and the adjacent plain to investigate flying activity of Nathusius' pipistrelle and common noctule bats at twelve sites over several weeks in the spring and autumn migration periods using automatic call recordings in order to answer the questions:

  • Do bat species migrate over a broad front across Central Europe?
  • Do bat species avoid mountains on their migration?
  • Are specific valleys in the German Central Uplands important migration routes?
  • Do bat species in the German Central Uplands prefer special small-scale terrain features such as valley slopes?

The functionality of light-sensitive geolocators was tested on three bat species for the first time in relation to bat migration. This addressed the following key questions:

  • Can the locators still measure light during the bats' activity periods?
  • Can geolocators attached to bats function over longer periods and is this compatible with animal welfare?

To test this, two types of locators with differing light sensitivity were used for short-term tests and the more powerful type also in a long-term test by using a specially developed collar on the animal in the wild.

The telemetry was designed in such a way that, at the start of the common noctule's spring migration, data points could be collected on the bats' positions as continuously as possible over as long a period as possible. This would enable the collection of information over the exact route taken and any detours during the start of the migration. The starting point was an overwintering location in the north of Switzerland. The main questions were:

  • Where do migrating noctules fly from and to and when?
  • For example, do they fly along specific features in the terrain such as mountains, valleys and watercourses?

In addition, isotope analyses from fur samples of almost 100 individuals provided information on the origin of the northern Swiss wintering population.



Migration of N. leisleri and P. nathusii takes place over a large distance. By contrast there is little population movement in N. noctula. A staggered movement of parts of the population which cannot be picked up in the data could hide larger movements. The migration pattern of V. murinus is more complex than supposed: the amount of data on this species is still too small.

Acoustic transect

The species appeared at 12 recording stations during the spring and autumn migrations, with two peaks visible everywhere in spring for N. noctula and P. nathusii. Individual identifiable migration nights are synchronous in all areas.

Migrating bats do not avoid mountains. Individual valleys do not play any special role and there is no preference for specific habitats or types of terrain. Activity in the three valleys in the German Central Uplands was similar and was due almost entirely to migration events. The high level of activity at the reference site (plain) was probably also due to animals looking for food and roosting sites and the autumn mating.


Short-term study: a low-intensity light chip can be used for N. noctula but a stronger type has to be used for N. leisleri and P. nathusii. A long-term study has not been successful so far.


In 2013 migration of female noctules from the overwintering quarters took place between the start of May and mid-June, in 2014 on almost exactly the same day. In two years the animals flew off in various directions between north-east and east. The route actually taken by two animals during the first half of the first migration night was documented relatively precisely: one animal moved away in a number of loops and "detours", thus increasing the actual distance flown. The migration route covered is therefore potentially considerably longer than a direct line between the winter quarters and the nursery. "Detours" can be explained by e.g. the search for food.

Wanderrouten der Fledermäuse

BfN-Skripten 453 (2017)

Practical application

The project results can be used in planning. With reference to wind energy in particular, the following results should be taken into account:

  • Migration over a broad front means that "migration corridors" for bats are unlikely: a cartographic presentation of the migration zone according to the current state of knowledge would cover the entire country. On the basis of current scientific knowledge, a map of bat migration routes does not seem meaningful.
  • The wind turbine operators can use bat-friendly operating algorithms in order to be able to make significant reductions in collisions on nights during the migration periods with high bat activity.
  • Roosting and mating areas (hotspots) of migratory species are important for maintaining the population: wind energy utilisation should be avoided in these areas.

Work packages

Work packages

  • Research, processing and analysis of phenological data for the four long-distance migratory species, the common and lesser noctule, Nathusius' pipistrelle and the parti-coloured bat.
  • Comprehensive research on current field methods and development of a research design for studying migration, taking into consideration and assessing current methods
  • Carrying out experimental pilot studies in open areas to examine migration routes using an acoustic transect, geolocator and telemetry

Project partners

Project partners

Project management

PAN Planungsbüro für angewandten Naturschutz GmbH
Rosenkavalierplatz 8
81925 Munich
Dr. Angelika Meschede
Tel.: +49 89 1228569-0

Project partners

NACHTaktivBiologen für Fledermauskunde GbR
Häßlerstr. 99
99099 Erfurt
Inken Karst, Wigbert Schorcht & Martin Biedermann

SWILD – Urban Ecology & Wildlife Research
Wuhrstr. 12
CH-8003 Zürich
Dr. Fabio Bontadina
Tel.: +41 450 68 05 / 06

Museum für Naturkunde – Leibniz Institute for Evolution and Biodiversity Science
Invalidenstr. 43
10115 Berlin
PD Dr. Frieder Mayer
Tel.: +49 30 2093-8702

Koordinationsstelle für Fledermausschutz in Nordbayern
(Coordination office for bat protection in Northern Bavaria)
Friedrich-Alexander-Universität Erlangen-Nürnberg
Department Biologie – Chair of Animal Physiology
Staudtstr. 5
91058 Erlangen
Matthias Hammer
Tel.: +49 9131 852-8788

Koordinationsstelle für Fledermausschutz in Südbayern
(Coordination office for bat protection in Southern Bavaria)
Hermann-Löns-Str. 4
84478 Waldkraiburg
Dr. Andreas Zahn
Tel.: +49 8638 86117

KFFÖ Koordinationsstelle für Fledermausschutz und -forschung in Österreich
(Coordination Office for Bat Protection and Research in Austria)
Fritz-Störk-Str. 13
A-4060 Leonding
Dr. Guido Reiter
Tel.: +43 676 7530634

Funding authority

Federal Agency for Nature Conservation (BfN)
FG II 1.1 Zoological species protection
Konstantinstr. 110, 53179 Bonn

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