It’s a hot day back at the road but here in the shade of Henry’s Bush it’s refreshingly cool. There’s the rushing sound of a waterfall off on my left, but I’m trying to ignore it, focusing all my attention on the grey box I’m holding. Did the signal get a bit louder just then? The person next to me is moving what looks like a cross between a supermarket trolley flap and an exploded lightning rod in a slow sideways arc.

“Stop” I whisper. “Move it back the other way a little bit.”

Around us are several other teams of two, all carefully sweeping the air in the same way. What on earth has brought us here, and what are we up to?

Bats.

When I found out the EcoQuest Education Foundation was holding a bat workshop in Patumahoe I knew I had to go. Despite knowing that bats had been detected on my property a few years ago, I knew very little about them and was keen to learn more. Having the chance to talk to an expert who has done bat tracking work all over New Zealand, and getting an in on the latest research? Sign me up!

It’s 2.00p.m. and nine of us are gathered together in the Patumahoe Junior Boys Rugby clubhouse. Each of us socially distanced behind a little personal table; it feels just like being back at school. But then David Clarke starts talking, and we’re hooked. An unassuming man with a clear speaking voice, probably as a result of all the talks he’s given, David’s remarkably modest about himself, and after only a brief introduction he dives straight in to talking about bats, and it’s clear where his passion lies.

Over a short time all of us bat-fans learn a huge amount. There used to be three species of bats in New Zealand, but only two species still survive: the short-tailed bat, which needs large areas of healthy bush, and the long-tailed bat, slightly more able to survive in the fragmented ecosystems that make up most of our land now. It’s the long-tailed bat the workshop is focusing on, as this one actually lives in Franklin, and we might even get to see one later on, though they’re very small.

An adult long-tailed bat

David tells us that long-tailed bats are unusual in that they don’t have a permanent roost site. A population (which can be up to 120 individuals) roosts at a site for only one day. After a night out feasting on moths (moths make up 90% of their diet, we learn) the bats settle into a new roost, which could be only 50 metres away, or as far as 7 kilometres from the previous one. Each night they hopscotch off over the bush and may only come back to a previous roost site once in a year. They don’t even all roost together, as they can split up over several sites for a day. This is one weird bat.

The whole class is rapt, firing off questions. Can we put up bat boxes for them? Yes, but current bat box designs are based on European designs, so might not be very attractive for NZ bats. There’s no harm in putting them up though, and some in Hamilton have been used by bats there. What are the main predators of bats? Cats, rats, stoats and possums are the worst ones, says David. His voice drops as he tells us about one incident where a hundred and two short-tailed bats were killed in just a week by a cat in the Rangataua Forest. One single cat can easily wipe out a whole roost of bats. A low murmur runs round the class.

After a pause, David dives into how bats can be detected. Tiny and dark, you’ll be very lucky to see one, and you won’t hear them, either, as their calls are far too high. He goes through the equipment used to detect them – some of which we’ll be using later on. There’s a microphone that hangs in a tree for weeks, recording everything around it in the right frequency.

He shows us how to read the recordings taken by the microphone to see if there are bats on them.

There’s a bat detector that converts inaudible bat calls into clicks that we can hear.

And finally the aforementioned supermarket trolley/exploded lightning rod, which is a radio tracking antenna. If you carefully catch a bat, and put a transmitter on it, using this gadget plugged into a receiver box you can follow the bat back to its roost. This is only possible because of fairly recent developments in radio tracking tags which are now small and light enough to be put on a bat without harming it. Later, David says, we’ll be tracking a bat.

A bat radio transmitter.

From many years of fieldwork and research, David’s nailed down the best places to find bats. Near water is good – bats like to drink often, and they like to snack on mosquitoes. Long avenues and pathways under tree canopy is also good, as it hides the bats from ruru who are bat predators.

And then class is over and we spill out, excitedly jumping into cars to follow David to Henry’s Bush where we’ll be practising radio tracking. Once we’re there he distributes the radio trackers in teams of two – one person to hold the antenna and sweep it around, and one person to carry the receiver box and watch the signal strength. Somewhere in this bush is a tagged bat. We have to walk in the direction of the strongest signal until we find it. It’s difficult work – we go a little way in one direction, then have to correct back as the signal seems to come from a different side. Everyone wants to try both roles, so there’s a lot of swapping about between who holds the antenna and who gets the box. Slowly the signal gets stronger until it’s at maximum. We mill around a group of a few trees, everyone getting a signal pointing to that area, but unable to home in on the right one.

Eventually we’re all excitedly circling a single ponga, waving aerials up and down it manically. If anyone comes by right now they’ll think we’re nuts. Still we can’t find it. At last, someone tentatively prods at a lump of dead leaves in the ponga crown and there it is – our bat!

Well, a plush toy bat with a transmitter stuck on it, anyway.

David laughs: “Now imagine trying to do that through miles of wild thick bush with no tracks, bashing your way up and down really steep gullies!”

On the spot, I develop a new-found respect for our intrepid bat researcher.

Flushed with our success in finding a cuddly toy, we grab a quick meal and then it’s off to find some real bats. The light is fading as we arrive at Martyn Wright Rd – perfect conditions, says David. Not too windy and not raining, the insects will be out, and so will the bats. In the dusk we wander along the road. I’m holding the bat detector tight, straining my ears. If a bat is nearby, the detector will translate its clicks into audible sound. A lone car goes by. If we looked nuts before, I can only imagine what the driver sees – a tramping club convention in the dark, not one of them looking up at the car. There’s a buzz from the detector and David yelps, ‘That’s one!’ He’s completely rapt. ‘I never expected to find one out here. That’s fantastic!’ His joy infects me, and I fist-pump the air. After all, we just found one of the rarest animals in Aotearoa just outside Patumahoe.

The fearless bat-finding team in Henry’s bush.

The course has been the experience of a lifetime. I’m already planning how to protect the bats on my patch better.

Predator Free Franklin and EcoQuest are collaborating on finding bat populations in Franklin. If you think you have bats on your property and would like to request the loan of a bat detector microphone for a week or so, contact David Clarke at David@ecoquest.co.nz