Why are wind farms so dangerous to vultures?

Cape Vulture sunning itself at VulPro
Cape Vulture sunning itself at VulPro

The people who build wind farms build them in higher lying areas where there are strong wind currents that can generate a lot of energy.  The problem is that birds like vultures use these wind currents as their highways as they glide for hundreds of kilometres looking for food.  Building wind farms in these areas guarantees that there are going to be collisions between the vultures and the turbines.

Big Blind Spots

Vultures’ eyes have also adapted to seeing great distances when they are searching for food.  With this wider field of vision, vultures have a blind spot directly in front of them, above and below their heads.  They are able to scan large areas of ground and maintain their peripheral vision to avoid crashing into vultures flying around them.   Scientists have studied vultures while they fly and have noticed that they also tilt their heads downwards which makes their blind spot even bigger, they also don’t constantly look around them; their field of vision is so broad that they don’t need to, this does mean though that it is very easy for them to miss things like wind turbines and power lines that are directly in front of them.

Slow Breeders

The damage done to vulture populations is worse than in some bird species which breed faster by having more than one chick at a time or breeding more than once  a year.  Vultures only have one chick a year their breeding season is quite short and they look after their chicks for much longer than the smaller birds do.  This means that it takes a breeding pair two years just to replace themselves in wild populations.  Vultures also mate for life, so there is no guarantee that when one of a pair dies, that the other bird will pair up and breed again.

Turbo Turbines

With vanes that can be 35m long and a tower can reach 65m high, the big industrial wind turbines may reach almost 100m up into the sky.  Though it may look like the wind vanes are turning really slowly, wind-turbine blades actually move really fast: The outer tips of some turbines’ blades can reach speeds of up to 288 kilometres per hour and can easily slice off a vulture’s wing.

Possible solutions

In Spain at one wind farm, vulture restaurants were created away from the wind farm and the turbines were shut down at the birds’ peak flight times.  In this case vulture deaths were reduced by 50% and only 0.07% electricity production was lost.

In Scotland, planners use maps to identify high risk areas for protected birds.

The Penescal wind farm in Texas uses radar systems to detect flocks of birds and shut off the wind turbines as they approach.

In Cadiz, Spain; teams experimented with temporarily stopping turbines when birds approached the wind farm they were so detailed that they looked at the individual turbines and shut down just those that the birds flight paths were destined to hit, this was called a “selective stopping protocol.”

References:

http://www.nature.com/news/vultures-blind-to-the-dangers-of-wind-farms-1.10214

http://www.sciencedirect.com/science/article/pii/S0006320711004927

http://www.nature.com/news/the-trouble-with-turbines-an-ill-wind-1.10849

http://www.savetheeaglesinternational.org.za/birds/vultures-blind-to-the-dangers-of-wind-farms/

http://www.science20.com/anthrophysis/preventing_windturbine_related_vulture_deaths-87867
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