8.10.2013: Forschung CH

Fledermäuse benötigen vernetzte Landschaft

Les chauves-souris ont besoin d’un paysage interconnecté


Annie Frey-Ehrenbold et al.

Vielfältige Struktur- und Vernetzungselemente in der Kulturlandschaft erhöhen die Anzahl Arten und die Flugaktivität von Fledermäusen. Dies wurde im Schweizer Mittelland an verschiedenen Fledermausgilden beobachtet.

Une diversité d’éléments structurels et de liaison dans le paysage rural augmente le nombre d’espèces et l’activité de vol des chauves-souris. Ceci a été observé sur le Plateau suisse pour différentes guildes de chauves-souris.


Agricultural intensification has caused a decline in structural elements in European farmland, where natural habitats are increasingly fragmented. The loss of habitat structures has a detrimental effect on biodiversity and affects bat species that depend on vegetation structures for foraging and commuting.
We investigated the impact of connectivity and configuration of structural landscape elements on flight activity, species richness and diversity of insectivorous bats and distinguished three bat guilds according to species-specific bioacoustic characteristics. We tested whether bats with shorter-range echolocation were more sensitive to habitat fragmentation than bats with longer-range echolocation. We expected to find different connectivity thresholds for the three guilds and hypothesized that bats prefer linear over patchy landscape elements.
Bat activity was quantified using repeated acoustic monitoring in 225 locations at 15 study plots distributed across the Swiss Central Plateau, where connectivity and the shape of landscape elements were determined by spatial analysis (GIS). Spectrograms of bat calls were assigned to species with the software BATIT by means of image recognition and statistical classification algorithms.
Bat activity was significantly higher around landscape elements compared to open control areas. Short- and long-range echolocating bats were more active in well-connected landscapes, but optimal connectivity levels differed between the guilds. Species richness increased significantly with connectivity, while species diversity did not (Shannon’s diversity index). Total bat activity was unaffected by the shape of landscape elements.
This study highlights the importance of connectivity in farm- land landscapes for bats, with shorter-range echolocating bats being particularly sensitive to habitat fragmentation. More structurally diverse landscape elements are likely to reduce population declines of bats and could improve conditions for other declining species, including birds. Activity was highest around optimal values of connectivity, which must be evaluated for the different guilds and spatially targeted for a region’s habitat configuration. In a multispecies approach, we recommend the reintroduction of structural elements to increase habitat heterogeneity should become part of agri-environment schemes.


Keywords:
Vernetzung, Landwirtschaft, Fledermäuse, Flugaktivität, Artenvielfalt



Literatur:
Frey-Ehrenbold A., Bontadina F., Arlettaz R., Obrist M. K. (2013). Landscape connectivity, habitat structure and activity of bat guilds in farmland-dominatied matrices. Journal of Applied Ecology, 261.
http://www.swild.ch/angebote/publi.html

Kontaktadresse:
Annie Frey-Ehrenbold
Eidg. Forschungsanstalt WSL
CH-8903 Birmensdorf

Annie.frey@swild.ch


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