Building roads that are 'best for bats'


Apr 18, 2017

Weighing in at just 8-11 grams, the NZ native long-tailed bat doesn’t register among the heavyweights of the wildlife or construction worlds, unless you're involved in the Hamilton section of the Waikato Expressway.

In New Zealand, the long-tailed bat populations are in decline and the species is now considered 'at risk'. And when you consider it's black, it only flies at night, it hides in trees during the day, and it makes sounds most of us can't hear, you begin to understand that the long-tailed bat's lifestyle has rendered it virtually invisible – and in need of protection.

The long-tailed bat has found a niche in Hamilton's southern gullies. And the more monitoring is undertaken for the Hamilton Section project, the more bats seem to be coming out of the woodwork.

One of the indirect benefits of expressway construction is the increased knowledge and understanding that comes from research and monitoring of native wildlife.

In Hamilton, monitoring of long-tailed bats along the Hamilton Section has shown they are more widely distributed than first thought.

While this has delayed some enabling works, the CityEdge Alliance remains committed to doing what's 'best for bats'.

Until this year, bats were known to inhabit the Mangaonua, Mangaharakeke, and Mangaone gully systems between Tamahere and Hillcrest, but they had not been detected north of Percival Road, Ruakura.
This meant that bat monitoring prior to tree-felling was required only on the southern half of the project. However, monitoring in 2016 has detected bats north of Percival Road.

To monitor bats, the project use acoustic bat monitors (ABMs) which measure the echo-location calls of long-tailed bats which has a distinct ultrasound frequency. The monitoring devices are placed in trees using long poles.

As a result, all trees are all monitored for bats prior to felling.

The Hamilton Section environmental management team has developed a Bat Management Plan for the project which has been submitted to the Department of Conservation (DOC) and the Waikato Regional Council (WRC).