Company confident a bat colony can be protected at a Canterbury wind farm site. David Williams reports
Protected long-tailed bats have been found near where the South Island’s biggest wind farm will be built.
The Department of Conservation says the discovery at Mt Cass, an hour’s drive north of Christchurch, is significant. “The long-tailed bat’s threat classification is nationally critical and there are only two other known populations on the East Coast of the South Island – near Geraldine and in the Catlins,” acting Mahaanui operations manager Anita Spencer says in an emailed statement.
MainPower, a community-owned company in North Canterbury, has consent to build a $200 million, 22-turbine wind farm at Mt Cass. It’s putting a positive spin on the bat find, on a neighbouring private property.
“It’s quite exciting for us,” says Scott Bennett, the wind farm’s project manager. “We’ll now go out and do further monitoring of the area to understand more about the movement of the bats, and basically to ensure how we can protect them.”
The company will work with DoC to “avoid, remedy or mitigate any negative impacts on their population”, Bennett says, which might range from deterrent measures through to pest management of the area they’re roosting in.
“This is something that can be managed. We won’t be the first wind farm that’s built in proximity to bat colonies. There’s a number of them already in New Zealand, with management plans in place.”
Spencer, of DoC, says: “It’s too early to say what this will mean for the wind farm.”
Long-tailed bats (pekapeka-tou-roa) are protected under the Wildlife Act.
Landcare Research ecologist Dr Norman Mason, of Morrinsville, is an enthusiastic bat fan. He says the find might present a headache for MainPower, but he’s not sure.
(Newsroom couldn’t raise bat expert Colin O’Donnell, of DoC, on the phone yesterday.)
Many pekapeka populations are vulnerable, as they live in highly modified landscapes. “They don’t translocate at all well,” Mason says, “so if you lose them from an area that’s it, they’re gone.”
The discovery gives MainPower the opportunity to have a role in biodiversity conservation as part of their operation. Research should be done into the Mt Cass roost’s habitual flightpath, Mason says, in case it takes them into where the turbines will be built.
Mason says it’s a wake-up call that the more we look for bats, the more we’re finding them. “We can’t really say that bats are definitely absent from areas just because we haven’t observed them for a while.”
This country has only two endemic land mammals – long-tailed and short-tailed bats, or pekapeka. They used to be common in South Island cities. In Christchurch, they roosted under the Avon River’s wooden bridges until 1885, DoC’s website says.
Long-tailed bats (Chalinolobus tuberculatus) weigh about 10 grams, with a wingspan of about 250mm, and zip through the air at about 60 kilometres an hour, within a huge home range of about 100 square kilometres. They’re aerial insectivores, feeding on the likes of moths, midges, and mosquitoes. Part of their echo-location call can be heard by people, because of its relatively low frequency.
(According to George Gibbs’ book Ghosts of Gondwana, New Zealand’s pekapeka are unique among bats for their broad omnivorous diet, the time spent foraging on the ground, and skeletal modifications that enable their ground-scuttling.)
Geraldine, in South Canterbury, is one of the few towns in New Zealand where they can be seen, flitting from giant totara and matai in Talbot Forest.
The find of long-tailed bats at Mt Cass presents a classic environment-versus-conservation problem.
As humans turn to energy-producing technologies to avoid fossil fuels, we’re having to consider other environmental effects, such as wind turbines’ threat to wildlife. Those risks inevitably increase as turbine towers grow in size.
International research suggests wind farms might be more harmful to bats than birds, and fatalities from wind turbines may increase the risk of extinction of some bat species. That’s because bats are some of the slowest reproducing animals on the planet. Mitigation suggestions include restricting tall turbine-use at night.
Construction is in the wind
MainPower’s Mt Cass wind farm, east of Waipara, was initially rejected by council-appointed commissioners in 2009 because it would degrade a nationally outstanding landscape.
Two years later, that decision was overturned by the Environment Court, after the company successfully argued there would be a net-gain in biodiversity through establishing a 127ha conservation management area. Last year, MainPower got an extension, to 2025, for the lapse of its consent, and a variation of conditions to use bigger turbines.
The 22 turbines, four fewer than initially proposed, will have blade diameters of 117m, for a combined capacity of 93 megawatts – enough to power 40,000 houses.
(The project’s been delayed. MainPower said construction would start last year but it’s yet to start. It’s now in the “develop-design” phase and construction is expected to start towards the end of next year, with the first group of turbines installed and operational 12-to-14 months later.)
Newsroom contacted Bennett, who works for MainPower subsidiary Mt Cass Wind Farm Ltd, last Friday, and he called back yesterday afternoon – an hour after news of the bat find was posted on its website.
He says DoC requested the company undertake bat monitoring prior to the wind farm’s commissioning, and it decided to get it done as soon as possible. It took place over two weeks in late November and early this month.
Bats were detected at five of the 26 survey locations, including one in the wind farm’s footprint. “At one particular location, the readings for the number of bats there was extremely high which indicated there was a colony present.”
That roost is on a private property “kilometres away” from the wind farm’s footprint. (The nearest long-tailed bat find to Mt Cass is thought to be 100km away.)
How will the pekapeka be managed? Bennett says it’s “very much early days”. “We’ve advised the property owner about the presence of bats on their property. We’re just waiting to hear back.”
MainPower notified DoC on December 14. Spencer, Mahaanui’s acting operations manager, says departmental staff haven’t visited the area “but believe the survey methods used are reliable”.
How is it bats weren’t previously discovered at Mt Cass? Bennett says they’re pretty elusive, very small and reasonably rare. Plus they only emerge at night. It’s also difficult and costly to search for them. He wouldn’t be surprised if there were other colonies detected further up the coast.
Spencer says DoC is working with MainPower and the Hurunui District Council, to follow an established environmental management plan.
Wind farm boss Bennett is bullish. His company’s committed to habitat protection and pest control work, as well as monitoring rare plants, like limestone wheatgrass, and lizards such as Canterbury gecko and McCann’s skink. Millions of dollars will be spent over many years.
“Without the wind farm happening you wouldn’t get this investment in the ecology and its enhancement,” Bennett says.
The question now is, how far and how often do the Mt Cass bats feed in and fly through the proposed wind farm site? The research is clear that wind farms across the globe kill significant numbers of bats, so you’d expect measures to be taken at Mt Cass to protect these nationally critical creatures.
The bat versus turbine battle has a touch of David and Goliath about it, with one big difference. At Mt Cass, the pekapeka were there first.