The story of the Matukituki Charitable Trust. Mt Aspiring National Park
An explanation of the relationship between biodiversity and trapping predators
This rather long post was put together originally as an evening talk on trapping to the Wanaka Vegetable Growers Club. It went down so well that I’ve now two more to give. And having assembled the photos it made sense to publish them here.
Before we get to the Matukituki Charitable Trust in Mt Aspiring National Park, lets look at different environments and how they differ in their own unique ways.
A typical braided river – The Hunter that flows into Lake Hawea, and some of the locals…
Black bill gulls. Homeless after a severe bank-to-bank flood. Thousands of their peers would have been washed away. And a banded dotterel playing at being injured to lure the photographer away.
Doing a braided river bird survey takes at least 4 very fit people. Who not only know their birds in spring time, but are also very capable at crossing the braids of the river concerned (occasionally grouping up for some serious crossings). They fan out mostly, in radio contact, and record everything they see in front of them as they walk downstream. Good weather essential.
Moving on to another environment…
A remote area between Lake Hawea and Tarras to the east, is host to the endangered Grand and Otago skinks…
This requires a different trapping regime, e.g. rings of traps placed around very steep bluffs, targeting mostly opossums and hedgehogs. Recently about 80 skinks were captured and relocated to safer managed areas in Otago, such as Macraes.
Now on with the real story…
The Matukituki Charitable Trust was set up in 2013 by Derek and Gillian Crombie, who are the founding Trustees. A partnership was entered into with DOC’s Wanaka Area Office Manager, Paul Hellebrekers. With the intention that it be a long-term project that would benefit species, the valley’s ecosystem and recreational users.
Photo: Derek (left) and Gillian (right) with Tait Electronics manager checking out VHF radios, donated by Taits.
Adventurer Bear Grylls and Julian Grimmond of the Mountain Film Unit in Queenstown also endorsed the project. NBC’s ‘Get Out Alive’ with Bear Grylls was filmed in the Matukituki valley in March 2013. Being enamored by the valley they donated $10,000 towards the project.
The logical base for field and trapping operations is the warden’s quarters at the historic and popular Aspiring Hut, in Mt Aspiring National Park. A facility owned by the New Zealand Alpine Club, and managed by DOC. The club readily gave the project their blessings
Photo: Two very interested local kea.
The first task was to establish which predators should be targeted!
Some of the early days team. Left to right: Gillian, Martin (very well known Cardrona based folk singer and song writer), Flo (DOC ecologist/bio diversity), Sharon (DOC Ranger), and myself Donald (volunteer)
Along the way between installing tracking tunnels and really getting serious about “upping” the trap numbers from a couple of hundred to several hundreds, we installed a few funnels. Beech tree seedlings obligingly drop into same, and they can then be collected and counted at regular intervals. The idea being to get good data on how much food is available for predators, season to season. From this, “masting”, years of prolific seeding, can be predicted.
Other means of gathering seeds are by helicopter, or by shooting branches. With a good aim with a large gauge shotgun firing a very heavy single bullet, the correct size branch, hosting ideal clumps of seeds can be “dropped” to the ground. The shooter will usually work from a steep slope, thus shooting outwards rather than upwards.
New Zealand falcon/kārearea with a mouse. Yes, common predator/nuisance #1 is the humble mouse. They tend to go into winter with large population numbers, and as food becomes scarce they become a means of survival and well-being for the various species of rat. Mum and dad rattus typically produce about 4 baby rats every 4-6 weeks. The less mice the better! But of course if numbers are low as the temperatures drop, the rats increasingly predate the native birds!
The real villains…
As mentioned above there are a few species of rattus. And they breed very fast and efficiently.
But the stoat is the real “shocker”: the father will impregnate his female off-spring. They then go off to “party up” killing for it’s own sake. And only when conditions are ideal, they’ll drop their litter. They’re increasingly migrating to higher altitudes in New Zealand also. Encouraged by climate warming for sure.
Opossum, our Australian import. They eat and destroy tons of forest canopy every night. They’re tree killers! In their home country they spend 90% of their time eating, and 10% mating. In New Zealand, thanks to the good tucker, it’s the other way round! They subsequently grow to very sizeable dimensions. Then of course need more food. Btw they will also eat eggs and fledgling birds. Their nemesis is peanut butter though.
Another nuisance is often very large gaggles of canada geese. Their poo is toxic, and they eat not quite like a horse, but certainly like a sheep or two. This throws the balance for the wading birds and ducks. The whio/blue duck being very endangered. They’re best controlled by someone riding shotgun in a helicopter (with the doors off), or by covert ground shooting with a 22. They’re surprisingly good eating, but maybe due to bad rap from farmers, no one seems to bother.
The locals that need protecting…
The south island robin was introduced to the valley about ten years ago and a bit. Approx. a doz. birds. This small population stayed stable near Aspiring Hut for a few years, helped by about 80 traps nearby. Then in 2014 with a “leg up” from the first of three 1080 applications, the population rose steadily. Prior to this of 4 fledglings hatched to each couple each spring, only one would survive. Once trap numbers were increased from 2014 on-wards, it became obvious that in most instances all four would survive. They’ve now spread all throughout the valley, and down around the corner into the East Branch, it’s thought.
During all this time regular banding was carried out to aid monitoring. As we speak the program is being wound up and a comprehensive report is being compiled. This will be an invaluable guide as to when the next species, mohua, is relocated into the valley from a healthy colony in Fiordland.
It’s not known if the mountain stone weta exists in the valley, but the possibility exists that it maybe there. If so it can’t help but have it’s existence assured by adequate control measures.
They’re so amazing that when temperatures drop to well below zero, their whole body can freeze down to -10°C for up to 17 days. When it warms again, they thaw out and come back to life as good as new, with no cell damage!
The kākāriki /NZ parakeet was the first species to reappear big-time after the program commenced in 2014. Prior to that the only evidence I came across while looking after the huts etc. was a bunch of feathers from a dead one. It had probably flown into the hut window, died, and was then eaten by the likes of a rat.
Our native owl the Ruru /morepork also reappeared not long afterwards. The one above though was mortally injured. I got it in a box, calmed it, and then carried it down valley on a Friday evening. After twenty minutes we met a DOC ranger who took it to the vet in Wanaka. But sadly it had to be euthanized the next day. There was little response to antibiotics – it’s wing was broken and maggot infested.
Their calls in the dark of the night is music to my ears. And occasionally they’d visit me. Attracted to the moths, who in turn were attracted to the hut lights. They arrive noiselessly due to their soft feathers. One night one of them sat with myself and one of my kea friends. Just hanging out enjoying the evening and each other’s company.
The idea behind the radio antennae is to attach a radio transmitter to female kea as it’s a very effective way to gain more knowledge when it returns to it’s nest. And hopefully also ensure fledgling survival. Often the technique is to install a trail camera in the nest, and one outside. Then surround the area with traps. Sadly the mother kea is very passive when nesting, and stoats have been shown to simply enter and help themselves.
There are an estimated 100 birds in the valley. This has probably stayed about the same from 2014 on-wards. In 2015 thirty two of them were filmed trying to vandalise a helicopter. It was shut down waiting for two people trapping to arrive for pickup. This confirmed a theory that the valley is a nursery. And like national parks world-wide; get the data and you can get the dollars (for conservation)!
Getting into the real work! Installing and checking traps.
Fords (not the vehicle type) often change during rain events. And then need to be tidied up. Sometimes it’s very hard and time consuming work.
The predator entry way for a DOC 200 trap, is via a hole in a grill. The attraction, or lure if you like, being an egg and a square of rabbit paste on the other side of the actual mechanism.. The cunning plan being to get the critter to cross the trigger plate. Which incidentally is so designed to not activate with the weight of a mouse. All trap types do have to pass tests to ensure they kill humanely. (an interesting word, humanely!) photos courtesy DOC
There is ongoing research into long lasting lures for traps. Good Nature manufacturers are always testing I think. After all, for self resetting units to be useful the lure needs a reasonably long shelf life.
The tried and true lure for DOC 200s is a fresh egg (every 2-3 weeks), and some rabbit paste (see above). Tests are also underway of satellite technologies, whereby a trap sends a text message, when it has been triggered. When refined, and coupled with long lasting lures, this will cut the manual labour considerably
Much has been written already about the benefits of 1080. As a side note though several years ago more had been spent by DOC on researching it, than had been spent on actual “drops”.
After the first application of the poison in the valley in 2014, I found the dead stoat as above. In due course after I’d retrieved it, it went to Christchurch to be examined. Also simultaneously a dead opossum was covered in wire netting, and every few weeks a sample of flesh was obtained, to establish how long the poison was staying in the body. Although 100mm of rain renders the poison harmless, it can linger in dead predators. Which of course could be eaten by a dog.
At Hells Gate, the entry to the west branch of the Matukituki Valley, approx., a hundred traps span the gap seen on the left. This is to stop predators, mainly cats, hedgehogs and ferrets, from entering.
Contentment! Morning tea break for the author while trapping. And not a single sandfly in sight 🙂
Recent News from the Matukituki Charitable Trust
On Monday 19 July 2021 Nikki Holmes (Operations Manager Central Otago) DOC and MCT signed a renewal of the Matukituki Management Agreement first set up in 2015.
<< Derek Crombie (MCT) and Nikki Holmes (DOC) signing the Management Agreement
Over the last 6 or 7 years The Trust and DOC have worked together to install the 852 trap predator control network, undertake species monitoring, deliver three 1080 programmes, remove about 5,000 pests and watched as numbers of South Island Robin, Kakariki, Kaka, Bell birds, Warblers etc have thrived. This work has been carried out with an excellent working relationship and each party has assisted the other to make it a very positive project. Twice yearly meetings have been positive exchanges of information and ideas to ensure the best practice is able to be delivered.
Mohua, maybe the next phase for the Matukituki Charitable Trust. Re-location back to where they once were in the Matukituki Valley.
photo courtesy DOC.
An alternative type of trapping with ferrets and a pack of dogs.
Nets and firearms are often used with this age old combination, e.g. the ferret flushes out a rabbit, then the dogs give chase until the rabbit runs into a net made of fine mesh. Noting here also that rabbit populations attract stoats, and that when they’ve killed off the rabbits, they then target birds.
One drawback though: Dogs and National Parks don’t mix! Legislation means they’re banned. And from a common sense point of view it’s also a good idea. They can do serious damage to populations, and often the owner has no idea, and will be in denial even.
Predator Free 2050
After trials in the Jackson and Arawhata valleys prior to 2019, Zero Invasive Predators (ZIP) and DOC focused on testing the validity of using extreme terrain features as a means of stopping predators repopulating large areas where they’d been eradicated.
It was very successful! Large cold rivers, mountain ridges and glaciers are a very real deterrent.
Dunedin as an example of achieving Predator Free 2050
In this blog post I’ve focused on trapping and biodiversity in terrain that is both vast, rugged and inaccessible. Around a city such as Dunedin the challenges are mainly social!
The city sees itself as NZ’s wildlife capital city. And it’s well on the way to maintaining this status. Catch phrases such as “lets get kaka back in the Octagon” have been used. Another goal I’ve heard of is aiming to have every forth household hosting a (backyard) trap. Of course education regards pet cat management will be needed.
The Silver Peaks, to the west behind Dunedin, are however pretty rugged. Which will add a further challenge on top of achieving social license from the public to really ramp up control. 1080 has already been used by OSPRI, who are charged with eliminating TB that opossum carry, (and spread to cattle). Control occurred on at least two occasions and gave a wonderful “leg up” to the several trusts working at bringing back the birds.
Orokonui Ecosanctuary / Te Korowai o Mihiwaka, in the Orokonui Valley between Waitati and Pūrākaunui, 20 km to the north of central Dunedin. It has been developed and is maintained by the Otago Natural History Trust. Such successful ventures in NZ generate what is called the “halo effect”. Where the bird population increases and spills over into adjacent habitat.
The ancient one at Orokonui. There are a number of free ranging tuatara that were reintroduced in 2012.
Related good news in Otago
OceanaGold have a laudable environmental program. It ranges from habitat restoration and conservation (snow grass/tussock mainly), through to skink and gecko colonies, and hosting/sponsoring a fish hatchery, maintained by Otago Fish and Game.
A last word on larger problem animals in New Zealand’s high country and National Parks
Himalayan tahr (Hemitragus jemlahicus) are large goat-like animals. Native to the central Himalayan ranges of India and Nepal, and not New Zealand. Thus they are not protected, and in fact are regarded/listed as “noxious/pests”.
photo courtesy DOC
Tahr are generally found in the alpine grassland zone, where they graze on snow tussocks, alpine herbs and sub-alpine shrub-land plants. They have no natural predators. In the fragile alpine environment they eat away the food source and shelter for the likes of rock wren and kea. It’s been estimated recently that there are 30,000 of them in the South Island high country.
Control has recently become an emotional issue. Many thinking that since legislation uses the word eradication, that this is possible. Currently it is not.
The species also supports a trophy hunting industry. Many hunters also cannot grasp that if herds reach starvation status, that trophy heads of bragging value simply won’t grow.
Good work has been done in the past by hunting associations and DOC on how to manage this animal. However the agreements reached, and work done have not been successful. Leaving management again up to DOC’s time proven methodology of shooting from helicopters.
A common question from the public, is why is the meat not retrieved. The answer is that since they inhabit very steep terrain, when shot the bodies roll and tumble considerable distances, and the meat is damaged (but kea of course can benefit from the fresh meat, especially pre winter). Also pick-up by helicopter of the carcasses is very technical and time consuming. The only feasible solution to harvesting the meat is to do the control in winter after deep snowfalls. If the cover is deep enough it slows the animals down considerably and stops the bodies rolling far.
Red deer are also listed as “noxious/pests”. Currently as of writing, populations are booming. Even in urban environments. This and a perceived right by many to hunt them for sport and food, is making control quite complex.
photo courtesy DOC web site