A third urban population of long-tailed native bats has been discovered, in Rotorua.

Until about 10 years ago, the threatened mammals were thought to live only in forests, but populations have since been found in urban areas of Auckland and Hamilton – and now in Rotorua’s Sanatorium Reserve.

The Rotorua Lakes Council said they were found in trees at two sites in the geothermal park, but their roosts have not yet been found.

Bats are New Zealand’s only native land mammals and although long-tailed bats (Chalinolobus tuberculatus) used to be common throughout New Zealand in the 1800s, they are now classed as ‘threatened – nationally critical’ and are a high priority for conservation.

“Population decline is mainly due to the impact of introduced predators,” the Department of Conservation’s Rhy Burns said in a statement.

“The risk to these bats is likely to be higher than in native forests due to the many human activities that occur in urban areas, as well as high densities of urban predators such as cats. Bats are usually hidden in cracks or holes in trees and cannot be readily seen.

“One implication of finding this population is that the presence of bats should be considered before any large trees are felled in the Rotorua urban and peri-urban landscape,” Mr Burns said.

Wildlands ecologist Sarah Beadel said in a statement she considered it a privilege for Rotorua to have bats so close to town.

“Bats are negatively affected by increasing light and traffic. They were located during a survey with acoustic monitoring equipment that detects their echolocation calls.”

It was uncertain whether the bats were only visiting the reserve at night, although there are trees there that would be suitable for use as roosts, she said.