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It has been claimed that due to their large size, and the velocity of their blades that wind turbines kill large numbers of birds that run into them at night, or in fog, and die.
http://www.wildlifeextra.com/go/news/wind-farm-birds112011.html#cr
Do wind turbines kill many birds each year?
Do wind turbines kill many birds each year?
In short:
An upper estimate might be of the order of half a million birds per year in the USA.
However it seems that hundreds of millions of birds are killed by collisions with other man-made structures. So wind turbines account for a small percentage of bird deaths attributable to human activity.
Nevertheless this can be a significant threat to the survival of some important bird species.
at night, or in fog
Wind turbines are hazard to birds (and other avians) in daylight. Bird evolution has evidently not incuded the necessary millions of years of exposure to non-catastrophic levels of threat from this type of fast-moving hazard. They are poorly equipped cognitively to recognise danger in any of these and other man-made hazards.
Some individual wind-turbine operators think even ten deaths per year per turbine is too many:
Primary school forced to turn off wind turbine after bird deaths
"We were told by the manufacturer to expect maybe one fatality a year but it killed 14 in six months so we took advice and made the decision to turn it off. "If it had happened at night time you could understand that the birds couldn't see the blades, which rotate at 135mph but it was happening at all different times of the day."
Large numbers of birds die every year from other causes, turbine-related deaths are currently alleged to be only a very small proportion of these.
According to a 2002 study A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions "funded by DOE, with direction and support from the Wildlife Working Group of the National Wind Coordinating Committee"
So the answer to the question depends on how many is "many".
More recent studies find higher numbers of avian deaths per year.
A 2016 study A preliminary assessment of avian mortality at utility-scale solar energy facilities in the United States included this table:
Table 2.
Estimated annual avian mortality from various sources
in the Southern California Region and United States.
Mortality source Southern California United States
region
Utility-scale solar energy
(USSE) developments 16,200–59,400 37,800–138,600 a
Wind energy developments 29,537–48,862 140,000–573,000 b
Fossil fuel power plants 3,561,600 14.5 million c
Communication towers 70,552 4.5–6.8 million d
Roadway vehicles >453,000e 89–340 million f
Buildings and windows >7,800,000g 365–988 million h
a Based on approximately 14 GW total name plate capacity of
utility-scale solar facilities in operations or under construction
across the United States [7].
b Sources: Loss et al. [36], Smallwood [23], Erickson et al. [24].
c Source: Sovacool [25].
d Sources: Erickson et al. (2005), Longcore et al. [33].
e Represents a minimum estimate using only estimated mortality for
paved roadways in the southern California study region.
f Source: Loss et al. [49].
g Represents a minimum estimate using only estimated mortality
for residential structures in the southern California study region.
h Source: Loss et al. [34].
I have not checked the dates of the references. It may be that this 2016 study is based on data from older studies.
Deaths for some bird species may be more significant than others: Scientists study wind-farm risks to birds
One survey at Big Horn Wind Farm in Klickitat County estimated that more than 30 raptors were killed during an initial year of operations — more than seven times the number forecast in a pre-construction study. The dead raptors included kestrels, red-tailed hawks, short-eared owls and a ferruginous hawk, which Washington state lists as a threatened species.
The simple answer is yes. The more complex answer is that the number of deaths is nothing in comparison to other man made structures and the risks from climate change.
There have been several studies done to find the environmental impact of wind farms on birds. Generally birds lack the ability to dodge humans and their quest for global supremacy. From the American Bird Conservancy there are a list of deaths related to sources as deaths per year in the US:
Feral and domestic cats - Hundreds of millions
Power lines - 130-174 million
Windows - 100 million to 1 billion (NB the high end seems too large to me)
Pesticides - 70 million
Cars - 60-80 million
Lighted communication towers - 40-50 million
Wind turbines - 10-40,000 (Table found here)
Obviously wind turbines aren't as popular as cars, cats and windows, but with the expected increase in wind energy generation, the impacts will likely increase. The thing that has to be borne in mind is that the wind turbines are on an order of magnitude smaller impact than other bird killers. It also has to be remembered that the studies are also showing that newer wind power plants are having less impact on birds due to design upgrades, better placement and better ecological planning.
The real issue here is climate change. Coal power plants kill birds, in fact, they are threatening to wipe out entire species. According to a study reported in Scientific American, at least 950 entire species of terrestrial birds will be threatened with extinction as a result of climate change under several scenarios, even at the lower estimate of temperature gains, just counting species of non-sea birds in the higher latitudes; outside the tropics. Birds in the tropics will be impacted by habitat loss, which brings the total species wiped out to ~1800 (Jetz, Wilcove, and Dobson 2007).
The take home point is that we need clean energy sources to save bird species. Those that fly into turbines each year will be minimised with better designs and locations of turbines. In the meantime, worry about the cats and climate change.
Update: recent studies have shown that birds of prey are more prone to injury and death from wind turbines. Essentially, birds of prey spend a lot of time looking down for prey and not enough time looking where they are going. The usual bird collision rate is 0.08 birds per turbine per day on average (range 0.05–0.19), whilst the 'smarter' Eagles are colliding at a rate of 0.112 to 0.133. The study also suggests that bird size and speed of flight are important determinants of collision rates, hence why gliding and hovering prey birds are colliding more often. It is worth bearing in mind that both of these collision rates (that often result in death) still indicate an avoidance rate of 99%.
This avoidance rate is important to compare to the relative deaths per gigawatt-hour of the power sources to realise that wind power is still a very good option. This study estimates that wind farms and nuclear power stations are responsible each for between 0.3 and 0.4 fatalities per gigawatt-hour of electricity while fossil-fueled power stations are responsible for about 5.2 fatalities per gigawatt-hour. Thus, wind turbines could do with some investigation into how to make them safer for birds, but they are already a much better option than fossil fuels.
