Surveys taken to protect native bats on Waiuku Solar Farm

Long-tailed bats (pekapeka-tou-roa) are one of New Zealand’s precious native species, and one of its most vulnerable, categorised as ‘Threatened - Nationally Critical’ by the Department of Conservation.

So when bats were spotted at the future Waiuku Solar Farm in Auckland, Lightyears Solar engaged ecologists to ensure that the bats were protected before, during, and after the essential tree felling on the site.

The work started with ecologist Jacqui Wairepo from Kūkūwai Consulting, who undertook bat surveys over 14 nights. She recorded flybys, feeding buzzes and passes, all of which indicated that bats were using the area. Survey nights do not need to be consecutive; they just need to be the right conditions: above 10 degrees Celsius, dry and clear, and done within a 30-day window.

The next step, this time by Wildlands’ ecologist Brent Henry, was to monitor bat activity for two nights before any trees were felled, using an automatic bat monitor (ABM). Again, they picked up activity.

“Because of the initial surveys, we knew that bats were likely to be present,” says Brent.

“The two days’ of survey prior to felling is due diligence to try and ensure that specific trees are not being used as habitat or as roost trees for bats. It’s about mitigating the risk of potentially injuring bats by having a good understanding of bat use of the site, to ensure that bats are not harmed during the tree removal process.”

A climbing arborist from Sharplin Treecare was then engaged to climb the trees. He did visual checks and used an endoscope to check for features in the pines and the eucalypts, including looking for active roosts or features like damage, flaking bark, and cavities, which can indicate that bats are using them as roosts. He communicated with Brent on the ground during these surveys.

The arborist was easily able to climb the tall, strong pines, but the smaller eucalypts were not as safe to climb, which meant he needed to redirect his ropes to descend onto the eucalypts from the pines and visually inspect trunk cavities using the endoscope.

Brent also stayed on site as each tree was felled, and a second arborist supervised tree splitting and removal.

Matt Shanks, Lightyears Solar development manager, says the tree felling was essential to construct the solar farm, which will provide enough renewable energy to power at least 500 homes, and they wanted to ensure that they did all they could to mitigate any risk to bats.

“We are committed to ensuring our farms are as low impact as possible, including protecting the natural environment and species already there during and after construction,” says Matt.

“Only exotic trees were felled for the project, and native plants are replacing them as screening for the farm.”

The felled trees will either be used as firewood, mulched on site to be used around the native planting or used to make furniture.