South Canterbury boosts roosting habitats of endangered bats

The Department of Conservation (DoC) has found a new use for old power poles in Pleasant Point, in south Canterbury. They could be key in bolstering the native long-tail bat's population. 

The pekapeka-tou-roa ruffled feathers when it won bird of the year in 2021. Common throughout New Zealand in the 1800s, the long-tail bat now has the highest threat ranking of nationally critical species. 

It's one of two bats in New Zealand, that are our only native land mammals. 

"There's only about 300 in south Canterbury which is very few. They could easily be wiped out in the next decade or so," DoC biodiversity ranger Simon Waugh said.

They're targeted by cats and stoats.

"They're also suffering from habitat loss, they need roost holes in trees to breed in and live in and in Canterbury there are very few trees for them," Waugh said.

That's thanks to tree felling, windy weather and farm development. And that's where artificial roosts come in. They're fixed to repurposed power poles, creating an alternative breeding habitat. 

"This is one of the designs we have, this is a German design edit," Waugh said. "Despite how small it is we'd expect 20 or so bats to fit in there."

Which actually won't be a tight squeeze.

"[They're] about 12 grams - about the weight of a $2 coin, sort of like a mouse with wings," Waugh said.

Artificial roosts exist in other parts of the country, but they are fixed to trees. Using old power poles is a first. 

There are two sites like this one. Both have 15 wooden poles, and each pole has a metal sleeve on it to stop predators from climbing up to the roosting boxes. 

It's too soon to tell if bats are using the roosts. DoC uses thermal imaging to monitor them, and in winter they'll swab for DNA.   

"It will be a good day when we finally see a bat in one of the boxes, we'd be stoked," Waugh said.

They're a stopgap while the native flora gain some height.

"If we can keep our maintenance on a really good regime and keep the weeds at bay we would hope to see some good vegetation at height in the sort of 10-15 year period," ECan biodiversity ranger Greg Stanley said.

That's when they may become roosts, so if you're thinking about firewood season, Waugh advises people to consider not chopping hoary willow or old trees.

You may not realise, but it could be a roost for New Zealand's only native land mammal.