August is Time to Go Bats in France
However this year events scheduled for the Night of the Bat are overshadowed by deepening concerns over the deadly impact that expanding numbers of wind turbines across Europe are having on often fragile bat colonies.
According to a Swedish study by scientists at Lund university published in 2012, a wind turbine in Europe or North America kills on average 2.3 birds and 2.9 bats per year. While these are median figures, the study goes on to say: ”For bats the most dangerous locations include coastlines and the top of distinct hills, but linear landscape elements such as lake shores, rivers, motorways, and, on a smaller scale also treelines, hedgerows and the like should also be considered as potentially risky…Bats are killed at wind turbines as they hunt for insects that accumulate around the turbine towers…”.
A French bat protection website run by SFEPM - Société Française pour l’Etude et la Protection des Mammifères says there are currently 20,000 wind turbines in Germany and nearly 5000 in France a number likely quadruple by 2020 when the government target for energy generated by wind is supposed to total 55 million mWh, or 10% of the total power consumption at that time.
“For the past 30 years, environmental studies have demonstrated the strong impact wind turbines have on bats. These highly curious mammals, have the dangerous habit of approaching the towers during seasonal migrations or during nocturnal hunts. Three types of bats are especially affected in France: noctules, the pipistrelle and serotine bats. European studies suggest a mortality rate at wind farms studied, that varies with the seasons and the type of turbine, making it difficult to approach to obtain a rigorous assessment and understanding of the phenomenon. In Germany the wind turbines’ impact is alarming — the lowest regional average figures suggest each turbine kills 2 bats a year, multiply that by 20,000 turbines and the number of bats wiped out annually become problematical. These are migratory bats whose females twice a year navigate their way through wind farms covering Europe to reach nests in eastern Europe.
“If nothing is done we could face a threat to the survival of this species in a few short decades. The risk is even more pronounced for Nyctalus noctula whose life expectancy is among the shortest of all major bat species in Europe. The pipistrelle Nathusius on the other hand favours coastal shores and inlets and its future is affected by the extension of future offshore wind farms”, says the SFEPM website.
Bats — which some refer to as flying insecticide bombers — are better than any chemical insecticide for controlling insects that attack farm crops, orchards and gardens. They devour half their body weight per night in various insects such as mosquitoes and other species including moths and act as an excellent natural insecticide, without the downside of soil poisoning posed by commercial insecticides.
According to an American report bats are “insanely” attracted to wind turbines for reasons that are unclear but among possible hypotheses are:
1. Auditory Attraction
Bats may be attracted to the audible “swishing” sound produced by wind turbines. Museum collectors seeking bat specimens have used long poles that were swung back and forth to attract bats and then knock them to the ground for collection. It is not known if these bats were attracted to the audible “swishing” sound, the movement of the pole, or both factors.
2. Electromagnetic Field Disorientation
Wind turbines produce complex electromagnetic fields, which may cause bats in the general vicinity to become disoriented and continue flying close to the turbines.
3. Insect Attraction
As flying insects may be attracted to wind turbines, perhaps due to their prominence in the landscape, white color, lighting sources, or heat emitted from the nacelles, bats would be attracted to concentrations of prey.
4. Heat Attraction
Bats may be attracted to the heat produced by the nacelles of wind turbines because they are seeking warm roosting sites.
5. Roost Attraction
Wind turbines may attract bats because they are perceived as potential roosting sites.
6. Lek Mating
Migratory tree bats may be attracted to wind turbines because they are the highest structures in the landscape along migratory routes, possibly thereby serving as ren-dezvous points for mating.
7. Linear Corridor
Wind farms constructed along forested ridge-tops create clearings with linear landscapes that may be attractive to bats.
8. Forest Edge Effect
The clearings around wind turbines and access roads located within forested areas create forest edges. At forest edges, insect activity might well be higher, along with the ability of bats to capture the insects in flight.
Resident bats as well as migrants making stopovers may be similarly attracted to these areas to feed, thus increasing their expo-sure to turbines and thus mortality from collision or barotrauma.
9. Thermal Inversion
Thermal inversions create dense fog in cool valleys, thus concentrating both bats and their insect prey on ridge-tops.
Watch this You Tube clip discussing growing concerns about the impact of wind farms on bats:
Currently, there are 34 species of bat in France. They are divided into four families: Rhinolophidés, Vespertilionidae, Molossidés and Minioptéridés. Most species have a wingspan of between 20 and 25 cm and a body length of 4 to 5 cm. However, some species can attain a wingspan of 40 cm (Noctules, Serotine, Greater Horseshoe Bat, Large Murin). The Rhinolophidés are all characterized by a nose in the shape of a horse-shoe and the presence of a nose leaf for ultrasonic transmissions. At rest they wrap themselves in their wings.
All European species are threatened which is one reason why the EU is coordinating campaigns to protect them.
In France the next national bat meetings will be held at Bourges in March 2014, while the 36th conference on bats — Mammalogy — will be held on 18, 19 and 20 October 2013 in Toulouse.
Many associations have joined the SFEPM to be part of the International Night of the Bat 2013. Contact: SFEPM c / o Natural History Museum, The Auron Rives – 18000 Bourges, Tel: +33+ (0)220.127.116.11.03 email: email@example.com
Join in the International Bat Night events – Saturday August 24 2013 — at sites all over France and in the overseas territories (Dom-Tom) see more details on the programme by clicking the image below.
Acknowledgments and thanks to Laurent Arthur – Muséum d’Histoire Naturelle de Bourges and Roman Pavisse – Secrétaire du Groupe National Chiroptères for the photos on this page taken from the nuitdelachauvesouris website.
The bat has been the subject of many literary and musical works and one of the most well known is Die Fledermaus (English: The Bat;’ French: La Chauve-souris’) an operetta composed by Johann Strauss II to a German libretto by Carl Haffner and Richard Genée.
According to Wikipedia: ”The original source for Die Fledermaus is a farce by German playwright Julius Roderich Benedix (1811–1873), Das Gefängnis (The Prison). Another source is a French vaudeville play, Le réveillon, by Henri Meilhac and Ludovic Halévy. This was first translated by Carl Haffner into a non-musical play to be produced in Vienna. However, the peculiarly French custom of the réveillon (a midnight supper party) caused problems, which were solved by the decision to adapt the play as a libretto for Johann Strauss, with the réveillon replaced by a Viennese ball. At this point Haffner’s translation was handed over for adaptation to Richard Genée, who subsequently claimed not only that he had made a fresh translation from scratch but that he had never even met Haffner.” Listen to the overture in honour of the Bat, below:
Story: Ken Pottinger
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