Well designed, modern wind farms present a minimal risk to birds and bats. In the 1970s and 1980s wind farms were constructed with little or no understanding of their potential impacts on birds. As a result, the problems specific to a few wind farm sites have created the perception that all wind farms present a significant risk to birds.
While current evidence suggests that birds and bat fatalities are not an issue at wind farms in New Zealand, developers do take care to ensure that proposed wind farms do not create problems.
Recorded bird strikes
Several windfarms are required through consent conditions to report any bird carcasses found during routine inspections. Since the opening of Te Apiti in 2005, 11 magpies, two harrier hawks, and one kingfisher have been recorded. A black-backed gull and a number of magpies have been recorded fatalities at Trustpower’s Tararua wind farm.
At the Brooklyn Turbine, which is located on a high spur immediately adjacent to the Karori Wildlife Sanctuary in Wellington, there has been one reported death of a blackbird, following a three month study. If strikes of significant species had occurred there is a high likelihood they would have been reported as the turbine is a popular tourist spot and visited regularly by sanctuary staff.
What are the risks?
Ongoing research has identified high risk factors for birds, such as:
- proximity to migratory paths
- lattice turbine towers encouraging perching
- large prey base in a wind farm site attracting birds of prey
- closely spaced or uniformly spaced turbines
- and transmission lines perpendicular to prevailing winds, or without flags.
These risks, if not well managed, have the potential to result in fatalities of birds and bats from collisions with wind turbines and other structures; electrocution from transmission lines; habitat loss; and displacement.
Managing risks
Wind farm developers acknowledge that for some species, the loss of a habitat or the death of a few individuals can have a major impact on local populations. A good knowledge of the wildlife present at a wind farm site and their behaviours, combined with careful siting of turbines and consideration of known risk factors, can ensure that a wind farm’s effect on wildlife is minimised.
Wind farm developers will prepare a detailed assessment of the species and habitat present in a wind farm site along with the risks the wind farm poses to these species. If necessary, the windfarm’s layout will be modified to reduce the risks. This assessment will normally form part of the resource consent application.
Wind farm developers can minimise the effects of a wind farm by:
- avoiding siting wind farms on migration routes and on bird habitat that is of conservation importance
- using ecologically sensitive construction and operation practices
- implementing a bird monitoring programme to improve the understanding of any potentail impacts on bird and potential mitigation measures
- restoring areas that are disturbed by construction and improving habitat for species that do use the site
- weed and pest control.
In New Zealand, predation by introduced species is a significant problem for birds. Pest control undertaken in a wind farm site will result in significant positive benefits for native species. Such benefits often outweigh the risk associated with wind turbines.
In addition, developers are often required, as part of their resource consent conditions, to monitor wildlife before and after construction to ensure the wind farm does not have unacceptable impacts on local wildlife. Monitoring revealed that in the first year of operation of the White Hill wind farm, in Southland, falcon breeding has been successful at the site.
Wind energy development’s overall impact on birds is extremely low compared with other human-related activities. No matter how extensively wind energy is developed in the future, bird deaths from wind energy are unlikely to be ever more than a small fraction of the bird deaths caused by other human-related reasons, such as predation by cats and collisions with windows, buildings and cars.