Concerns about the number of bats and birds of prey being killed by wind farms are creating obstacles to wind energy expansion in some parts of the world. The slow down is particularly marked in wind energy flag bearer Germany where development of new farms has slowed to a crawl. With many more towering wind turbines expected In New Zealand in the next few decades, MICHAEL DALY looks at what is known about the impacts on wildlife in this country.
The sharp decline in German wind energy expansion is particularly notable because of that country’s commitment to a switch to renewable energy through its Energiewende energy transition policy.
In a statement in July, the German Wind Energy Association (BWE) said construction of wind turbines on land in Germany fell to the lowest level since the year 2000, in the first half of 2019.
Just 287 Megawatts or 86 turbines were added during the six months. When dismantled turbines were included in the calculation, the net increase was only 231MW or 35 turbines. Nature and species protection were by far the main cause of opposition to new wind farms, BWE said.
In this country, the Department of Conservation said the risks posed by wind farms to birds and bats were not fully understood.
An indication of its concerns can be seen in a submission on a 24-turbine wind farm proposed for the Kaimai Ranges. The submission said DOC opposed the application, but was not opposed to the wind farm in principle. It considered the application did not adequately address issues dealing with birds, bats and other wildlife.
Wind Energy Association chief executive Grenville Gaskell said monitoring at New Zealand wind farms had shown no significant bird strike issues. Also international research showed by and large that the risks to birds from wind turbines was very low, with other human-related activities posing far more significant risks.
International research also showed wind energy posed a lower risk to birds than other types of electricity generation, Gaskell said.
Meanwhile, in Germany an attempt to calculate the number of insects killed by wind turbines in that country came up with the “rough but conservative” estimate that the figure was somewhere around 1.2 trillion a year.
That was nearly 1100 tonnes of dead insects, the 2018 paper from the German Aerospace Centre said. Analysis has indicated sharp declines in flying insect biomass in several nature reserve areas in northern Germany in recent decades, but the wind farm paper said it was not possible to make any reliable statement about the contribution of wind turbines to that reduction.
In Australia, a few eyebrows were raised in July when former Greens leader Bob Brown, among his numerous campaigns, opposed plans for a substantial wind farm on Robbins Island in Tasmania. The risk to shore birds was a key part of his reason for opposing the project.
In recent months regulatory and court decisions appear to have brought an end to two large wind farm projects in the US – in Oregon and North Dakota – with concerns about the risk to birds of prey, including eagles, a factor in both cases. Reports indicate there’s still plenty of wind energy development in the US, but there can be strong opposition, including from conservation groups, if a proposal is considered to be in the wrong place.
The American Wind Wildlife Institute, which includes representatives of industry, conservation groups and researchers, estimated in a summary earlier this year that a substantial majority of birds killed by wind turbines were small, and that the number killed was much smaller than the number of bird deaths related to other human activities.
Populations of those small birds were not at risk from wind turbines, but modelling indicated a potential for population-level impacts for some raptor species, including golden eagles, the summary said.
Diurnal raptors – those active during the day – accounted for about 8 per cent of reported bird deaths, which was more than expected considering the number of such birds. The summary said that could be because those birds were more vulnerable to collisions with turbines, or because carcasses of larger birds were easier to find.
In many countries there has also been dismay at the number of bats killed by wind turbines. The US Geological Survey is among the agencies trying to work out what is going on.
Bats were being found dead beneath wind turbines all over the world, USGS said on its website. It was estimated tens to hundreds of thousands died at wind turbines in North America each year.
“Widespread deployment of industrial wind turbines is having unprecedented adverse effects on certain species of bats that roost in trees and migrate.”
In New Zealand, DOC said wind farm impacts were monitored in line with resource consent conditions, and were administered by district and regional councils.
As for what is known about wind farm impacts on wildlife in New Zealand, it pointed to two documents from 2009 – one of bird species of concern at wind farms, and the other a review of what was known internationally about the impacts of wind farms on birds. The review said it was difficult to determine the magnitude of wind turbine-related bird fatalities at New Zealand wind farms by extrapolating from studies elsewhere.
DOC also pointed to two documents from 2013 – one on bird death monitoring at Project West Wind near Wellington, and the other an assessment of the risk posed to New Zealand falcons.
The Project West Wind monitoring was carried out during two years from September 2009 to August 2011, and published in the New Zealand Journal of Zoology. Described as the first comprehensive study at a New Zealand operating wind farm, it involved fortnightly carcass searches at each of the 24 turbines being monitored.
In the two years of the study, 53 turbine-related deaths involving 18 types of bird were recorded. Harriers had the highest death toll, with 12. The next most deaths were six chaffinches – an introduced species – then five paradise shelducks, which are native but not threatened.
A native fairy prion was the only at-risk species found at the study turbines, although another at-risk species – sooty shearwater – was incidentally found at a non-study turbine site. There were no recorded deaths of falcon, kākā or kererū.
Based on the findings, it was calculated that each of the 64 turbines in the wind farm was responsible for 5.83 bird deaths in the first year of the study and 4.64 deaths in the second year. As part of the process of developing those estimates, efforts were made to work out what proportion of birds killed were found during monitoring.
The effort to estimate the total number of birds killed at the wind farm came up with the number 363 in year 1, comprising 308 very small, 18 small, 15 medium and 22 large birds. In year 2, the calculation indicated 289 bird deaths, of which 156 were very small, 28 small, 28 medium and 77 large.
In its submission on the Kaimai Wind Farm proposal, dated January, DOC said the proposed project area, on the north western area of the Kaimai Ranges, south of Paeroa, provided suitable foraging and roosting habitat for the threatened long-tailed bat.
DOC did not accept enough was known to support the conclusion in the consent application that the project’s effect on bats would be low. “The loss of any bats will affect this population and could contribute to local extinction,” DOC said.
The project area also contained, or was likely to contain, many threatened or at-risk birds, as well as other non-threatened birds. “The proposed wind turbines have the potential to kill or injure most species of birds present or likely to be present at the site, including those that are migrating or dispersing through the site,” DOC said.
DOC wanted more information about bird behaviour and habitat use at the site, and said more monitoring was needed to determine likely effects of the proposed wind farm.
Information provided by applicant Kaimai Wind Farm Ltd, a wholly-owned subsidiary of Ventus Energy (NZ) Ltd, referred to bat monitoring carried out at the 28-turbine Te Uku wind farm in Waikato, which became fully operational in 2010.
Consent conditions for Te Uku had required bat monitoring of up to five years, but it was decided by DOC, the councils involved and owner Meridian Energy to end the monitoring after three years.
“Two additional years of bat monitoring would have been required at that site if monitoring indicated a decline in bat activity post-construction, or if any evidence of adverse effects on bats was obtained through strike monitoring,” the applicant’s information said.
The DOC submission on the Kaimai project said the monitoring at Te Uku was considered to be insufficient and did not support a conclusion that the impact on bats at Kaimai would be low.
No bat carcasses were found during three years of monitoring at Te Uku, but removal studies used to assess searcher efficiency showed most tiny carcasses similar to bat size were quickly removed. So no bat carcasses did not mean no effect, the DOC submission said.
Search intervals at Te Uku were also too long, relative to the known low detection and high scavenger rates confirmed using test carcasses. That meant any bats killed at Te Uku were likely to have been scavenged or to have been undetected.