By the Editors of Conservation Times
Habitat loss and fragmentation are the greatest impacts of wind farms on wildlife. Wind turbines, like many other human activities and buildings, also increase the death rate of avian creatures such as birds and bats.
A summary of the existing field studies, compiled in 2010 from the National Wind Coordinating Collaborative, identified fewer than 14 and typically fewer than four bird deaths per installed megawatt per year, but there was a wider variation in the number of bat deaths.
Like other investigations, it concluded that some species (e.g. migrating bats and songbirds) are known to be harmed more than others. However, many details, as well as the overall impact from the growing number of turbines, remain unclear.
4th Highest ‘power”: India has the fourth highest wind installed capacity in the world with total installed capacity of 35.6 GW (as on 31st March 2019) and has generated around 52.66 Billion Units during 2017-18.
Tamil Nadu has maximum total wind capacity at 8,631 MW. Gujarat houses the secondlargest capacity in the country, total at 6,044 MW. Maharashtra houses the third-largest capacity at 4,789 MW. Karnataka houses the fourth-largest capacity at 4,584 MW. Rajasthan houses the fifth-largest capacity at 4,300 MW.
Wind power installations in India reached 2.07 GW during 2019-20, a 31% increase as compared to 1.58 GW during the previous year. Wind power represents 10.1% of the total installed power capacity in India during 2020.
The Wildlife Institute of India (WII) researchers have estimated the mortality rate of Great Indian Bustard (GIB) due to high voltage power distribution lines by picking up the carcasses from under the windmills and power lines to record meticulously the number and type of birds killed as a result of collisions.
A quarter million mortality: Based on such scientific data, it is extrapolated that nearly 1,20,000 birds are killed each year through collision with windmills and power distribution lines in Desert National Park and the areas surrounding it. Some wildlife conservationists have argued that the need of the hour is to underground the existing transmission lines, urgently and immediately, and that no new transmission lines in critical GIB areas which have been identified should be permitted.
Double edged: This is a double-edged sword. On the one hand power is being generated, which is termed as clean as is without pollution, but on the other hand this green technology is playing havoc with bird populations. But no development comes without a cost. The need of the hour is to scientifically assess the issue of windmills and its impact on bird populations and to urgently find solutions which are compatible.
Bird Diverters: The Government has issued guidelines to windmill developers and operators to take risk mitigation by putting up bird diverters on the windmills and transmission lines and paint the vane tips of the windmills orange color to avoid bird hits. Researchers of the WII are working on the effect of bird flight diverters which, on the basis of data collected, appear to be effective to the extent of reducing bird deaths by about 20%.
Birds Main Victims
Collisions and electrocutions of birds at power lines have long represented a major conservation issue, and the current proliferation of electrical infrastructure is increasing this threat. Globally, collisions with power lines may cause more than one billion annual bird deaths Between 10 and 41 million birds are likely killed each year by power line collisions in Canada. In the United States, rough estimates of annual mortality range from hundreds of thousands to 175 million collisions, and from tens to hundreds of thousands of electrocutions.
This amount of mortality would rank power lines above other structures that kill birds, including wind turbines and communication towers. Furthermore, mortality at power lines may contribute to population declines for some species, as evidenced by studies documenting that power line-caused mortality can cause a large percentage of total mortality for species from several avian orders.
Power line collisions occur when birds fly into wires; electrocutions occur at poles when a bird completes a circuit by touching two energized parts or an energized and grounded part. Correlates of mortality rates include: (1) biological factors (e.g., bird age, size, and wing span for both threats; maneuverability, flocking behavior, and vision for collision); (2) environmental factors (e.g., topography, vegetation, and prey abundance for both threats); and (3) structure-related factors (e.g. line orientation and distance between wires for both threats; exposure of and distance between energized and grounded parts for electrocution).
Whereas electrocutions occur primarily at distribution lines–small power lines with voltages between 2.4 and 60 kilovolts (kV)–collisions occur at both distribution lines and transmission lines–large power lines with voltages >60 kV. However, relatively few collision studies have been conducted at distribution lines; those that have suggest that there is little difference in collision rates between line types. Both sources of mortality are reducible with the use of retrofitting measures or with implementation of bird-safe standards at new construction.
Despite an increasing number of studies that employ rigorous a priori study designs, much of the research published to date about bird mortality at power lines has consisted of qualitative reviews and assessments of opportunistically collected data. Furthermore, nationwide estimates of mortality at U.S. power lines are speculative or based on extrapolation from a single European study.
Policy and management for reduction of wildlife mortality should ideally be based on evidence from scientific studies that implement randomized and replicated sampling schemes (hereafter “prospective studies”). In addition, national-scale estimates of mortality and comparisons among mortality threats are likely to be used for prioritizing policy and management strategies and for identifying major research needs.
Study by Scott R. Loss, Tom Will, and Peter P. Marra
The U.S. Fish and Wildlife Service is especially concerned about growing impacts to some 836 species of migratory birds currently protected under the Migratory Bird Treaty Act of 1918. Communication towers may kill from 4-50 million birds per year. Collisions with power transmission and distribution lines may kill anywhere from hundreds of thousands to 175 million birds annually. , and power lines electrocute tens to hundreds of thousands more birds annually, but these utilities are poorly monitored for both strikes and electrocutions. More than 15,000 wind turbines may kill 40,000 or more birds annually nationwide, the majority in California.