Wind farms do kill animals in flight, but not always the obvious ones. Bats, not birds, appear to be the main victims of land-based wind turbines in the US, according to a report by the US National Research Council.
Surveys at wind farms reveal a surprisingly high number of bat carcasses, the NRC reported on 3 May. Although the evidence is patchy, the council warns that wind farms might eventually have an impact on bat populations in the US. Two species – the hoary bat and the eastern red bat – suffer most, accounting for over 60 per cent of the 2500 kills recorded.
Bats are renowned for their aerial skills and it’s not clear why they can’t avoid the relatively slow-moving blades of wind turbines. The council suggests that high-frequency noise from the turbines’ gears and blades could be disrupting the bats’ echolocation systems. The problem also seems to be worse at wind farms on forested ridges, perhaps because more bats are attracted to such insect-rich places.
With wind energy expanding rapidly in the US – a record 3000 megawatts of new power capacity was installed last year – the report says that research is urgently needed to assess whether the technology will damage bat populations. Bats are relatively long lived and produce small numbers of offspring, so communities may find it hard to recover if turbines cause many deaths. On the plus side, the NRC finds that the threat to birds does not appear to be serious.
NewScientist.com news service
12 May 2007
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