Batty about night visitors

New Zealand bats are endangered. Photo / James Reardon

Bat fever is rising as interest in the winged creatures soars.

Bat expert Brian Lloyd says reported sightings in some urban areas have jumped this year and attributes this to a rapid rise in the use of bat detectors, which turn ultrasound bat signals into sounds audible to humans. Bat enthusiasts, ecologists and educators are the main users of detectors.

Hamilton ecologist Darren Le Roux, known to locals as "Batman", says there may be bat populations in Auckland that have escaped detection. "Because they are such cryptic animals, they could be in many places we haven't looked at."

He believes bat detection could also become a lucrative tourist industry - if the creatures can avoid extinction.

Waikato Museum offers night-time bat-detection tours led by Le Roux. He runs the excursions during school holidays and says people of all ages tag along. "It's exciting. People aren't aware that there are bats in Hamilton."

A variety of hand-held bat detectors are available for sale online. Most cost between $500 and $1000.

Users set the device to a frequency of 40KhZ, the bats' echo-location range.

"You normally orientate it in the direction you think the bats will be," Le Roux said. "Then the sounds picked up will be transferred into an audible sound."

Dr Lloyd said: "It's suddenly taken off. I know a guy that manufactures bat detectors in New Zealand. He sold over 600 in the last two years."

New Zealand bats fly at 60km/h and can cover vast distances. Dr Lloyd says freak winds and wild weather can disperse bats into cities.

"They do get around an awful lot. Like Happy Feet."

But people interested in bat detection might need to be quick. Dr Lloyd says bats are on a rapid trajectory to extinction.

Stoats and ferrets prey on native bats, which evolved without anti-predator strategies.

"The only thing that's more unique to New Zealand is probably the tuatara." Left in peace, New Zealand bats can live for decades. Department of Conservation biodiversity ranger Hannah Edmonds says bats have an exceptional lifespan compared with other small mammals, living up to 30 years. DoC estimates long-tailed bat numbers will fall by about 90 per cent by 2050.