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Bats and offshore wind turbines studied in southern Scandinavia 2005 - 2006 Bats & Wind Energy Cooperative Workshop 8-10 Jan. 2008. BCI, Austin, Texas.

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Presentation on theme: "Bats and offshore wind turbines studied in southern Scandinavia 2005 - 2006 Bats & Wind Energy Cooperative Workshop 8-10 Jan. 2008. BCI, Austin, Texas."— Presentation transcript:

1 Bats and offshore wind turbines studied in southern Scandinavia 2005 - 2006 Bats & Wind Energy Cooperative Workshop 8-10 Jan. 2008. BCI, Austin, Texas Ingemar Ahlén, Lothar Bach, Hans Baagøe, & Jan Pettersson Presented by Ingemar Ahlén

2 Bats and offshore wind turbines studied in southern Scandinavia 2005 - 2006 Swedish Environmental The ’Vindval’ Swedish Energy Protection Agency program Agency Ingemar Ahlén, Lothar Bach, Hans Baagøe & Jan Pettersson Bat photo: Björn Söderlund

3 Project management and persons taking part Ingemar Ahlén, Professor, Ph.D., zoologist. Dep. of Ecology, SLU, Uppsala. Project leader. E-mail: Lothar Bach, Dipl.-Biol, zoologist. Bremen. Assistant project leader. Hans J. Baagøe, Ph.D, curator, The Natural History Museum of Denmark, Zoological Museum, Mammal section, University of Copenhagen. Taking part in the Öresund area 2006. Tommy Gustafsson, biologist, County administration in Kalmar. Field assistant. Alexander Eriksson, biologist, County administration in Kalmar. Field assistant. Petra Burkhardt, biologist, Bremen. Analyses of data from Kalmarsund 2006. Julia Lopau, biologist, Bremen. Taking part in Kalmarsund 2006. Dave Karlsson, entomologist, Uppsala university, Ecological research station, Ölands Skogsby. Sampling insects. Kajsa Glemhorn, entomologist, Uppsala university, Ecological research station, Ölands Skogsby. Identification of insects. Svante Martinsson, entomologist, Uppsala university. Ecological research station, Ölands Skogsby. Identification of insects. Jan Pettersson, ornitologist. Färjestaden. Radar studies in Kalmarsund. Lars Pettersson, Senior lecturer, electronics expert. Development of ultrasound technology for the project.

4 Baltic Sea Gotland Öland Sweden Denmark Germany Finland Estonia Latvia Lithuania Poland Norway

5 Migrant bat species in Scandinavia have to cross the sea for hibernation on the European continent. But 15 years ago we didn’t not know how and where they travelled. From National Atlas of Sweden. Geography of Plants and Animals 1996. Stockholm

6 Available knowledge at the start of the offshore project: •Migration of bats studied at the coasts since 1993 •Pilot studies of landbased wind turbines in 2002-2003


8 On land we discovered flyways leading to certain points. Bats often followed the coastlines in August and September

9 We also found flyways along linear elements such as forest edges and the stone dike on the picture

10 Points at the southern coasts with concentrated flyways were found. Bats could easily be observed and recorded there. This is Ottenby where most bats leave Öland for the continent

11 Hoburgen, the southern point of Gotland The point where bats leave the island of Gotland in the middle of the Baltic Sea Distance to Polish or German coast about 250 km!

12 Bat fatalities were discovered for the first time in September 1999

13 160 wind turbines were investigated in August-September 2002

14 Where bat fatalities were found in 2002 (17 bats of 6 species)

15 Results from the pilot study in 2002-2003 in Sweden: • Bats, migrants as well as non-migrant species are killed by turbines, mainly in August and September • Hypothesis about acoustic attraction falsified or not supported by experiments • Hypothesis that migrants shut off sonar not supported by observations and recordings • Insects accumulate around turbines which attract bats to stay hunting there • The windmills with frequent bat foraging were the mills where fatalities were found • High risk sites were found along the coasts, near wet meadows and lagoons, but also in some forest areas • Low risk sites on open agricultural land without linear elements

16 What happens out there when we lose sight of them? Do they go on in concentrated flyways? Do they use the normal sonar we know from land?

17 On Öland we knew two important take- off points. Bats go out there heading straight towards planned offshore wind farms Red dots = Wind turbines Black dots = Planned turbines

18 Objectives Bat behaviour when passing or hunting at offshore wind turbines Activity in the areas planned for windpower Find out, if bats are exposed to risks Factors that might influence the risks, e.g. geographical position, flyways, insect abundance and weather situation Suggest how risks can be minimized Investigations needed before locating Control program during build-up Photo: Mikael Gustafsson

19 Investigation area in Kalmarsund. Observation sites in 2005 och 2006.

20 Observation sites in Öresund, between Denmark and Sweden, 2006.

21 m/s Skagerack in the harbour of Degerhamn, Öland. Utgrunden offshore windmills. After testing some boats we chose this one, a stable norwegian service vessel. Almost noise-free when listening and recording ultrasounds.

22 Approaching the wind farm Yttre Stengrund off the coast in Blekinge

23 When listening and recording from the boat the engine and radar must be off The strong searchlight was useful to spot bats passing the light beam at long distance and to assess the abundance of insects Autobox for recording was placed here

24 Ultrasound detector D1000x with headphones

25 Ultrasound detector D940x with digital recorder Edirol R-09

26 Portable 12V spotlight (Q-Beam) powered by two 6V rechargeable batteries (Mila Safepack)

27 “Autobox” for automatic recording of time-expanded ultrasounds This was the 2006 version. Next season a digital high speed recorder with capacity for several days will be available.

28 Autoboxes for automatic recording were hanged up with a telescopic rod

29 We put out Autoboxes on 5 + 7 offshore windmills and got bat sounds in all places.

30 Utgrunden lighthouse where the radar for bird and bat migration was operated

31 Flight routes from two bats passing Utgrunden lighthouse One went straight south, the other one was obviously checking the insect abundance and disappeared to the southwest Photo: Jan Pettersson

32 Abbrev.Scientific nameSwedish name MbecMyotis bechsteiniiBechsteins fladdermus MbraMyotis brandtiiBrandts fladdermus MdasMyotis dasycnemeDammfladdermus MdauMyotis daubentoniiVattenfladdermus MmyoMyotis myotisStörre musöra MmysMyotis mystacinusMustaschfladdermus MnatMyotis nattereriFransfladdermus PnatPipistrellus nathusiiTrollfladdermus PpipPipistrellus pipistrellusPipistrell PpygPipistrellus pygmaeusDvärgfladdermus NleiNyctalus leisleriLeislers fladdermus NnocNyctalus noctulaStor fladdermus EnilEptesicus nilssoniiNordisk fladdermus EserEptesicus serotinusSydfladdermus VmurVespertilio murinusGråskimlig fladdermus BbarBarbastella barbastellusBarbastell PaurPlecotus auritusLångörad fladdermus PausPlecotus austriacusGrå långörad fladdermus Bat species found in Sweden (18) and Denmark (17)

33 SpeciesMm/bMdauMnatMspPnatPpipPpygNleiNnocEnilEserVmurPaurChirS:a Observations in 2005 Over the sea, Kalmarsund 53031481479163154 Radar observations 425 On land, Kalmarsund 252471201281111800975021411578 Total 2005 2577712013112122815695932042157 Observationer in 2006 Over the sea, Kalmarsund 445848141118214728253587 Over the sea and islands, Öresund 19203161229 182 Radar observations 2564 On land, Kalmarsund 118423626647077124415181454116946 Total 2006 162102347271048401640481701128341510197 Total 2005 and 2006 266917942485822606817461722911510341912 354 Mdas Number of observations in Kalmarsund and Öresund in 2005 and 2006 In 2005 and 2006 we made a total of 12 354 bat observations, 3 830 over the sea and 8 524 on land. Bats of 10 species were observed on the open sea and 13 species at the take off sites on land.

34 Here at Hoburgen I made a remarkable discovery…

35 …some bat species landed on vertical cliffs and crawled around for nocturnal invertebrates.

36 Spider, net, and chironomids in the boat gunwale

37 Foraging at sea Available prey organisms: Nematocera: Chironomidae, Cecidomyiidae, Culicidae, Tipulidae Trichoptera: Leptoceridae Hymenoptera: Ichneumonidae Lepidoptera: Noctuidae Crustacea (Idotea sp, Amphipoda) In suitable weather (low wind speed) we found an enormous abundance of insects in the air and in the water surface. Sometimes we think that bats also took crustaceans in the surface. Migrants as well as resident species used this food source in late summer and early autumn.

38 Most of the migrating bats leave the take-off points during the first hours of the night. They will arrive in Poland or Germany next day in full daylight. In spring we get them back in the late mornings often with full sunshine. Bats that are out for insect hunting have a peak later in the night. This probably coincides with the best insect hours. This could vary throughout the season. These data from the radar shows an example of this:

39 Activity was very much influenced by weather. The data from a take-off site show that the highest number of bats occurred the night with the lowest wind speed.

40 Bats passing in relation to wind in the middle of Kalmarsund strait according to radar observations 2006 (mainly Nyctalus noctula )

41 Auto- Boxes Ottenby, southern point of Öland Flyway over land north of Ottenby Activity in relation to wind

42 Detector observations Passing bats and wind at Ottenby Pipistrellus pygmaeus Pipistrellus nathusii

43 Flight altitude at sea Transport flight Most bats we observed and recorded when they were migrating (not hunting) passed at relatively low altitude. From close to the water surface to a few tens of metres. The radar studies confirmed this. The majority of the passing bats (mainly Nyctalus noctula) were observed below 40 m, only a few higher up. Hunting flight When bats are hunting things are quite different. They use food sources from the surface up to almost any height where they find it worth searching. They could move from the boat level to the upper parts of the mills in a minute. Hunting near the blades, however, was only observed at low wind speed. That Nyctalus noctula in southern Sweden is hunting insects at an altitude of 1200 m above the ground was proved by thermal camera recordings at Falsterbo. The height of the tallest wind turbine is therefore negligible if there is food in the air.

44 Risk assessment at offshore facilities Collisions • Risk for collision is higher when bats are flying close to the moving blades repeatedly than just passing once (On land we found killed bats just where they stayed hunting close to the mills in suitable weather). • Therefore they are more exposed when hunting insects that are attracted to the upper parts of the mills. • Insect hunting was most often observed at low windspeed and calm weather. • It made no difference to the hunting behaviour, whether the blades were moving or not. Roosts in generator house (nacelle) Bats appear to rest inside the generator house regularly. Such roosts might expose them to electrical installations there.

45 About further research One important thing to do: • To go on studying bat activity, flyways, feeding areas etc offshore our coasts and this is irrespective of wind power plans. • Find out where and how bats, migrants and residents, make use of the enormous food resource. • This is probably the best way to find general patterns of scientific value and will give a better background to predict problem areas.

46 Ahlén, I., Bach, L., Baagøe, H.J., & Pettersson, J. 2007. Bats and offshore wind turbines studied in southern Scandinavia. Swedish Environmental Protection Agency. Report 5571. 37 pp. Stockholm. Ahlén I., 1997. Migratory behaviour of bats at south Swedish coasts. Zeitschrift für Säugetierkunde 62: 375-380. Ahlén, I. 2003. Wind turbines and Bats – a pilot study. Final report to the Swedish National Energy Agency 11 December 2003. Dnr 5210P-2002-00473, P-nr P20272-1. Ahlén, I. 2002. Fladdermöss och fåglar dödade av vindkraftverk. Fauna och flora 97:3: 14-22. [Summary: Bats and birds killed by wind power turbines.] Link for downloading the publications (pdf) above:

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