Native bats are something few New Zealander’s know exist, let alone have ever seen. With two species living in Fiordland local rangers undertake monitoring in order to protect and learn more about these special little critters. We join the team after they have caught their very first short-tailed batin the remote Murchison Mountains.
Having caught the first Murchison Mountains short-tailed bat the next step is to attach a transmitter to it so that we can radio track it to its roost. Bat transmitters are necessarily small, just 0.6 of a gram so as to not be over burdensome to a 15 gram bat. Larger animal species can have transmitters that last for a year or more, allowing rangers to constantly track the same individuals for long periods of time, but a transmitter that weighs less than a gram has a battery life of only a few weeks. This also means that bat transmitters are attached temporarily with glue rather than a more permanent set up such as a backpack harness on a takahē.
Trialing new techniques on a rare species can lead to great improvements or they can fail terribly. Glue is imperfect and across the country rangers have the same problem of bat transmitters falling off anytime between 3 days and 3 weeks once attached, it’s an unpredictable lottery. The quest for a magic glue that will remain firmly attached for 3 weeks without harming the bats has long been sought-after. Our team has a new type of glue to try, one that has been used on bats in Europe with good reviews. Our first bat has its transmitter attached this way. The following day we radio track it and find the glue has failed, the transmitter lays dropped on the forest floor. Back to the drawing board on the glue front, and back to mist-netting bats for us.
We are in Fiordland, well known for its rain, especially this spring. Rain is a problem for us in many ways, we can not handle bats with wet hands in fear of getting moisture close to their skin and giving them hyperthermia. When it’s pouring with rain they don’t bother flying anyway and then there is the river. It rains for two days. When it stops enough to try catching again the river is still unsafe to cross so we head to our mist net site set up closer to home on our side of the river. Alas we still have wet feet due to the side streams, it is definitely a wet boot trip.
Not all bats are created equal (sorry boys) and by 2am we have only caught two males. The breeding females of both long-tailed and short-tailed bats roost in colonial maternal roosts, allowing for far easier and more reliable monitoring, these are what we are after. Males sometimes visit these roosts but spend most of their time sleeping in solitary roosts rather than leading us to the mother lode. By 2am our feet have turned to ice blocks so we return to camp, have a hot drink and game of cards to wake up before returning to the mist net site. Dawn arrives slowly through the trees, our count remains at two males, it’s time to head home.
By now we can cross the river to the other side and set up a new net site further up valley. And it’s jackpot time with 11 bats caught in little over an hour. We put two transmitters on females (with our old glue). But despite the 11 bats caught it’s a ruru/morepork that steals the show for the evening flying into our mist net in the dark. Ruru are the natural predators of our native bats and are seemingly attracted to their noise. Our squeaking to attract the bats also draws them in and they have been a constant companion at all out net sites. This is the first to fly into our net though and we can’t help but enjoy in the opportunity to see one up close up and marvel at it.
With more rain coming in, it’s time to fly home and have a shower. Our two transmitted bats will have to wait until next time.
Follow the team to see how they get on in the third post and follow the series here.
Native bats are something few New Zealander’s know exist, let alone have ever seen. With two species living in Fiordland local rangers undertake monitoring in order to protect and learn more about these special little critters. We join the team heading into the remote Murchison Mountains hunting down short tailed bats.
It turns out that the Murchison Mountains have more hidden gems than just takahē, with an acoustic recorder picking up the sound of a southern short tailed bat (STB for short) in 2018 in the Ettrick Burn Valley. These devices are designed to be placed in the field and can “listen” for the echolocation of both long and short tailed bats as well as recording all manner of bird calls, wind, rain and river noise. Short tailed bats are notoriously hard to detect as they only emerge after dark and these recorders are the easiest way to get an idea about where they live.
Excitement reigned after the initial discovery but the questions came thick and fast — how many bats were in the valley? Was the population doing okay? Did they come from the neighbouring population 40km away? These detections made the Ettrick Burn bats only the third southern STB population known to still exist. So in the summer of 2019 with the help of some sponsorship from the “Breaksea Girl” charter boat in Fiordland, a 3 person team headed in to catch these bats and try to track down some more.
But how do you monitor an animal that is nocturnal, lives in holes up trees, weighs less than a mouse and can number in the thousands in one colony? With a truck load of equipment! Equipment to climb trees, special bat traps, infra-red video cameras and batteries, data loggers and more batteries, tents, a generator to charge the batteries, countless pieces of safety equipment, food for a week, the list goes on. So much we overflowed the helicopter.
The first task was setting up camp, we were based out of a small two bunk hut the “Log Cabin”, named after the original built by Dr Orbell in the early 1950’s but a log cabin no longer. It’s pretty small to say the least and so we were all sleeping in tents but it provided a space to cook and stay dry. With camp set up we turned to finding net sites and preparing for the night. Reflectors were stuck to markers to guide us home in the dark and likely catch sites were identified.
Trying to catch the first bats was a bit like looking for a needle in a haystack. We knew they should be roosting somewhere in the valley but had no idea where, with our net covering all of 10m long by 2m high. As bat’s echolocation picks up shapes in the dark we use a special bat mist-net to try and fool them. It’s made of thin threads of silk woven together to form a diamond pattern of air and feels like a spider web, it certainly sticks to you like one.
By 10pm it was finally getting dark enough for the bats to emerge and so we started squeaking on bird callers which attract them. At 10.05pm the first Ettrick Burn short-tailed bat flew into our net, the first of this new population.
Stay tuned to the Conservation blog to follow the team to see how they get on in the next post and follow the series here.
In the world of conservation, species management at a population level is very different to that at an individual level — especially when it comes to our beloved alpine parrots and their notorious curiosity. This is a deep dive into our programme of work for kea, and the evidence-based decision making within it.
Our staff are passionate about what they do.
And, honestly, the word passionate undercooks it a bit.
The team are knowledgeable, enthusiastic, committed, and deliberate; and above all, determined to halt the decline of New Zealand’s critically at-risk native species and protect our natural biodiversity. It’s a goal shared by all conservationists, volunteers and scientists, as well as members of the public.
The trick is managing for multiple conservation outcomes, especially in cases where we need to protect different species in the same habitat.
That’s where DOC has a palette of hard choices.
We’re the agency charged with conserving Aotearoa’s natural and historic heritage. And make no mistake, our biodiversity is in crisis, with more than 4,000 of our native animals and plants threatened or at risk. The most damaging animal pests are possums, rats, stoats and feral cats.
In large, remote, inaccessible areas; predators like stoats are absolutely running rampant and wreaking havoc on precious taonga species. Take for instance:
Pekapeka/bats, our tiny native land mammal! They’re in serious danger of extinction.
Kākāriki karaka/orange-fronted parakeet, our rarest parakeet! There’s only 100-300 left.
Kiwi, our flightless icon! Of which we’re losing 2% of our unmanaged birds every year.
To manage these precious species, we have some tough choices in front of us. All of our decision-making is evidence-based, fuelled by research, and made in conjunction with partners — because conservation is too important to do any other way.
Not all of our decisions are universally popular – although by and large, the majority of the New Zealand public understand that doing nothing is not an option.
Although it’s never straight forward.
Research on kea and 1080
Like kiwi, the kea population is seriously threatened by stoat predation. Kea nest in holes in the ground that are easy for stoats to find and get in to. Nest failure climbs to more than 90% in a stoat plague, which is the year after beech or rimu forest seeding.
Kea are clever, curious birds, and a taonga species of cultural significance and importance to Ngāi Tahu.
They also take trolling to a new level – one kea learned to turn on the water tap at the Aspiring Hut campground; another locked a mountaineer inside the toilet at Mueller Hut; and one more lifted about NZ$1300 cash from a tourist’s campervan when it was left unattended.
They’re the Einsteins of the ngahere/forest that’s for sure.
Aerial 1080 is the only proven predator control tool we have available to treat the rugged and remote habitat kea call home.
Research shows the success of kea in raising young following a beech mast is high after aerial 1080 predator control (about 70%), but very low without it (about 10%).
Long term studies of kea populations have proven an overall benefit from 1080 predator control after a forest mast (seeding) event, despite the loss of some individual birds.
Which is to say: at a species level, kea benefit from aerial 1080.
But at an individual level, it’s more difficult because – well, they’re kea, and they get into everything.
Kea tamper with (and get caught in) traps; they get lead poisoning from eating nails and flashings off buildings; they play in traffic in high-visitation sites; and they put pretty much everything in their mouths.
And, unfortunately, some birds have eaten 1080 pellets as well.
It’s like when a few bad eggs ruin something for everyone else – except no kea are bad eggs, they’re either just highly inquisitive birds, or they’re doing what we’ve taught them.
In places where kea have become accustomed to finding non-natural food (things left behind by people — think lollies, rubbish, leftover lunch, etc etc), some of them are far more likely to pick up a brightly coloured bait.
Scrounging is learned behaviour. And kea are very quick learners.
The situation can be summarised as this: we have a population of notorious avian scroungers at risk of extinction due to predators; a few of whom have scrounged the pellets which can control the predator numbers and save the whole species.
It’s conservation catch 22.
DOC-led research published in 2019 reviewed kea survivorship through 19 aerial 1080 operations between 2008 and 2016. Almost all deaths occurred in operations within 20km of scrounging sites, and/or where there had been no recent use of 1080. Meaning if kea are accustomed to scrounging, they’re more likely to do it to baits; and we’re working to understand why they occurred in areas with no recent use.
In new treatment areas, it’s much harder to predict what kea will do. That’s why we are trying to monitor the relationship between kea that scrounge, or have been exposed to 1080 before, and whether or not they eat the bait.
While we’re working on how to protect this species, you can help by not feeding individual birds, and making sure there’s no litter left behind in the environment.
Since 2014, there have been three revisions of the Code of Practice for Aerial 1080 in Kea Habitat (a publicly available document designed to make the best use of aerially applied 1080 while minimising negative impacts on kea populations long term) and each revision has been in response to new evidence. The third edition, released at the beginning of 2020, was in response to the new evidence that identified likely causes of why kea deaths occur in some operations but not others.
The Wet Jacket Operation
Last month we completed a (long-awaited) aerial 1080 operation at the Wet Jacket peninsula in Fiordland to protect tokoeka kiwi from stoats.
The need for this operation was urgent.
Over three years, our team conducted intensive monitoring of critically rare Fiordland tokoeka kiwi nests to evaluate the impact of stoats. It was part of the Save Our Iconic Kiwi programme, which you may have read about in our blog series: The Fiordland Kiwi Diaries.
The blogs in the Fiordland Kiwi Diaries series are a must read. They document the monitoring of 34 kiwi chicks in the Shy Lake area over 3 years.
And not a single kiwi chick survived.
This was virtually always due to stoat predation (in about 88% of cases, the chick was killed by a stoat — which is 30/34 chicks).
This is Waimarie, the first chick discovered. She was killed by a stoat when she was only about 20 days old.
Rinse and repeat for pretty much every single chick.
It was heart breaking.
If it were to continue without intervention, there would be no future for this taonga species, the tokoeka kiwi.
The Wet Jacket aerial 1080 operation was crucial for kiwi survival, but it was also an opportunity to fill gaps in our kea research because the remoteness gave us intel on whether kea unaccustomed to scavenging would still be inclined to pick up baits.
What we learned
Since 2019, we’ve been monitoring 21 kea in the Shy Lake area using radio transmitters, although only 6 transmitters were still active prior to the operation. (The others may have fallen off, malfunctioned or the birds been killed by predators) and we are continuing to monitor kea in the area in coming weeks.
Sadly, three monitored kea died following the operation, and post-mortem and toxicology testing confirmed 1080 as cause of death.
The proof that some kea will still eat baits even if they’re not from scrounge sites or acclimatised to the scrounger life is a significant development.
Wet Jacket taught us that more research is required to understand kea behaviour (our current focus is around threat mitigation and adaptive management) to protect as many birds as possible during an aerial 1080 operation.
While we (obviously) don’t like losing individual kea, we know that at a population level, kea do better with 1080 predator control than without it, and this operation was necessary to prevent kea and Fiordland tokoeka kiwi from being decimated by stoats.
There are possible kea deterrents like anthraquinone, an agent that make kea feel sick, or leaving out tahr carcus as a decoy (which basically works by being like a massive, ‘hey kea, over here, eat this instead!’ sign).
The tahr distraction technique shows promise, but these mitigation methods need to be properly trialled, including understanding differing variables like time of year, altitude, and ensuring the kea population in the area are radio-tagged. We’re looking to trial this method in an upcoming operation.
While we’re working to improve practice and drive down risk, aerial 1080 is the only proven tool we have available to manage the number one threat to kea over its expansive rugged mountain and forest habitat. There’s nothing else right now that we can deploy with our available resources at a scale able to provide population benefits to kea – and kiwi, and pekapeka and native flora and fauna.
At the end of the day
Our biodiversity crisis is serious, and the road to recovery is paved with tough choices.
It’s critical that when we make these choices, we’re well informed, and can confidently say that the pros outweigh the cons.
Research is ongoing to make sure we’re learning as much as we can and have hard evidence to inform our decision making. Because ultimately, we need to pull out all the stops to halt the decline of New Zealand’s critically at-risk native species.