I’ve known for years that the cost and logistics of managing and eventually eliminating the introduced predators that are killing off our native bird species is not possible with trapping alone, and that even if it was we would not have enough people in New Zealand to do the job, man, woman and children included, yet many think we can.
Which gets pretty weird, but maybe this is because an estimated 80% percent of the population are urban dwellers. Then another factor is that 70% don’t think we have a problem!
Well we do! Here is one of the main culprits [by the way in less damp terrain the humble hedgehog is also, along with the stoat and feral cat, up there high on the list of the most efficient killers of birds].
This dead stoat was retrieved by myself high up on the track to Cascade Saddle in Mt Aspiring National Park after the application of 1080 in the West Matukituki Valley in 2014. The “find” was rated so useful by the Dept of Conservation that a 4wd vehicle was dispatched immediately on recipient of my radio call, and the body taken out to Wanaka and then sent off for a pathology report. Such is the detail sought after and attended to by DOC!
And so here we have below some mind boggling figures for trapping just a small portion of New Zealand’s native bird habitat – published today in response to a highly publicised statement by the Society for the Prevention of Cruelty to Animals:
The SPCA’s suggestion that trapping could replace toxins is totally naive. Let’s look at the logistics:The Department of Conservation is looking at treating 1 million hectares of conservation land with 1080 this year. To do just 250 hectares of trapping, targeting multiple species as 1080 does, you’d need to cut trap-lines 45km long, in grids through the forest. Let’s multiply that by just the conservation land in Northland alone. (116,000h/250h) * 45km = 21,000 km of trapline – which is enough to wrap halfway around the planet. Then you’d need 420,000 rat traps,
Since this was published in lots of local papers a few months back, now seems a good time to republish, given that since then we’ve seen new heights of unimagined hysteria regarding how DOC and the Govt. continue to use 1080 successfully in vast areas of our landscape, that we can’t access easily, and even if we could the cost effectiveness of trapping would not be sustainable.
That cost effective mind set relies on people power too, paid or otherwise. And here is the thing: even if we could deploy millions of traps, there’d not be enough people to service them, even if every man, woman and child in NZ got on the job.
Here are a couple of older photos of mine of the Landsborough area. It’s big! The river valley runs all the way from Mt Cook National Park to Haast, parallel to the main divide, with the additional Hooker Range to the west.
The cliffs in the photo below were called “The Kea Cliffs” by old time mountaineer explorers who thought the birds nested in such places. Sadly this is not true – they nest on the ground and are easy prey for stoats, rats and cats.
20-year DoC project in South Island valley shows value of pest control. A 20-year effort at the Department of Conservation’s longest-studied area for pest control has led to native bird numbers doubling – an encouraging sign for New Zealand’s bold predator-free 2050 mission. A programme in South Westland’s Landsborough valley is DoC’s longest study charting the response of birds to pest control, giving conservation scientists insights into what approaches work in beating back predators. Predator control b
There are cautionary things to be learnt from being under a bird – things that can come back to haunt us from childhood:
I was about four years old when hand-in-hand with my mother, like my hand in hers while my other held a flavoured and much savoured ice cream. All was good I recall, until suddenly with a plop, a passing sea gull dropped a deposit on it. I was gutted, but perhaps it was good start to training for life!
Fast forward a few too many decades to when I was recently working 6-7 months a year up the West Matukituki Valley in Mt Aspiring National Park looking after huts, and also monitoring birds and doing some trapping; all in an ice cream free zone.
It was the beginning of a relationship of sorts with four NZ falcon / kāreareas. The two parents had accepted me so it became the norm for them and their fledglings to hang out nearby, notably in the early autumn when there would be some serious training going on that was all about catching mice in the long grass by Aspiring Hut. It became a fascinating privilege to have them around me albeit ignoring me in a sort of aloof way.
A juvenile learning to hunt for mice, using hearing more than sight, but make no mistake they’re very aware of the slightest movement in the grass even when airborne and 30-40 mts away…
This juvenile failed to find a mouse for lunch so flew up into a nearby tree and made such a racket hoping the nearby parents would supply some food – none was forth coming however…
Adult NZ falcon / kārearea with a fresh lunch at Aspiring Hut…
Three years on and the family had shifted a little down valley, but I was remembered as I awkwardly squirmed under this alpine shrubbery, and then even more awkwardly got the camera activated and pointed upwards. The bird literally yawned and then got on with dealing with an itchy ear, while I’m less than two meters away!
So that was one thing going on in the West Matukituki Valley near Wanaka, where predator control is on-going after a significant upscaling of same back in 2014 by the Dept. of Conservation [DOC] and the Matukituki Charitable Trust.
In a nut-shell it’s working with an increase of all bird species, to the point that people staying in the valley at Aspiring Hut this summer past of 2017-18 reported that the dawn chorus woke them up too early!
Amongst an impressive line up of New Zealand song birds the melodious bellbird / korimako takes line honours in the “what a lovely day for singing my best tunes” stakes. They are also very clever at being able to mimic other sounds they encounter, even other birds, or noisy plumbing pipes in a lodge…
The flighty tomtit is one of the indicator species that signals that the bird habitat is getting back in balance to their advantage. The other being the rifleman and south island robin / toutouwai. All are increasingly evident in the area…
For two years now we’ve delighted in the valley to hear again the haunting calls of the morepork /ruru at night. We’ve seen them with fledglings too, and even hanging about Aspiring Hut catching moths drawn to the light, where they delight with their ability to arrive in a ghost like manner with absolutely no wind noise. Gentle souls! This one I got to know quite well after discovering him with a badly damaged wing. Sadly it’d been fly-blown, and the injury was not survivable despite vet intervention and antibiotics…
And of special note, because they’re such an expensive species to help, is that kea numbers have increased – the valley is indeed still a nursery…
To get to this happy point required much planning and thousands of hours of work by volunteers and DOC staff.
What gave the birds a real “leg up” in the initial stages was an aerial application of 1080 poison, one that I was actually present for, as in living in the area and monitoring results. Then the installation of hundreds of new traps got fast forwarded by getting a large DOC Community Fund grant to buy them, and when done the bird populations got the most significant boost ever when the valley qualified again [based on gathered data] for another 1080 application in the spring of 2017.
And while we don’t know so much about numbers of predators that have died of poison, we do know that 3958 have been trapped by various trusts and DOC in the seasons 2016-17 and 2017-18 between Wanaka and the West Matukituki operation, as discussed here. The information is very detailed now as well, so hot-spots can be identified [relative to species of predator], and the choice of lure and trap types refined.
Here are some photos of some of the stages:
Finding out which species of predator needed to be knocked back in numbers meant installing tracking tunnels – an awkward task at best, but very necessary…
When the line is set up then at regular intervals during the year an inked card is placed in each tunnel overnight. What hungry critters are about are attracted to a lump of peanut butter in the centre and after a nibble they leave tracks on departing. By contrast an opossum will simply pull the card out and partially rip it up…
Carrying these slick funnels designed to catch beech tree seeds [so as to be able to predict how much food in advance will be available to predators] was another memorable job, especially in dense bush and up and down steep banks – not one I’d like to repeat often! The stakes are used to support the funnels, which are fitted with some panty-hose at the bottom…
DOC staff and volunteers counting beech seeds – a fun evening. Each handful, which were shot down in this instance with a shotgun/large calibre bullet, was host to about 100 seeds…
Traps now totalling almost 800 have been installed from way down the valley by Mt Aspiring Station to above Liverpool and French Ridge [pictured] huts, even in terrain that is snow covered in the winter. At this altitude the at risk species is the amazing rock wren, which hibernates under the snow for the winter…
Training up fit and competent teams to safely service the traps and tunnels in this typical southern alps terrain was another step along the way…
Installing a virtual barrier of traps to stop the migration of predators wishing to enter the valley was carried out at Hells Gates just a few Km upstream from Mt Aspiring Station’s homestead it is comprised of about 110 traps offset at 50 mt spacings, across this gap…
Here are a few thoughts on some of the details and relationships that need to be considered and planned for in any “big picture” project like this one:
Of all predators the cat is the hardest one to entice into either a live catch cage, or the likes of a DOC 200 trap, and has to be lured in, often by laying food outside until trust is established over a number of days. Also cats apparently have a range of 20kms. It’s a fickle and time consuming exercise.
Education is critical for cat control, political or not. Education of children is very effective, then they go home and pester the parents, and simultaneously hopefully talk them into back yard trapping and home moggie management.
Meanwhile targeting the rabbits for miles around is known to be effective. Stoats for one will also travel vast distances for a tasty rabbit, and when they get scarce the stoat then targets birds. I imagine the same applies to ferrets and cats. Eliminate rabbits and the problem diminishes.
Dead stoat and eggs used for lures…
Mice are another critical species to get under control, and that’s a challenge all over NZ!
Since a rat plague usually follows on from a mouse one, [which follows a prolific seeding of trees, which follows warmer seasons].
It’s been a definite advantage in the valley to have 4wd access, but every now and then after a severe rain event, the road has to be repaired…
The opossum numbers have to be quantified also, and appropriate strategies worked out to get their numbers down, and then the quality of the forest habitat soars in favour of the birds.
Baby opossum near Wilson’s Bluff. A little usual to see one like this in broad daylight, but it was sick I think, as it had a damaged eye and was very sluggish…
Lastly hedgehogs seem to hold a special place in the heart of NZ gardeners, but are known to be as efficient as a stoat at eating eggs and killing fledglings. More education required here too, and despite their tiny legs they’re now found and trapped at relatively high altitudes in our remote high country and even in damp environments such as braided river deltas.
Tools of the trade, a DOC 200 trap and lures used such as rabbit paste. I think the local robin / toutouwai knows the benefits of good gear – actually while trapping it is quite normal to become friends with the locals, and to cement the relationship scuffing up some moss and dirt to reveal grubs is good form….
South Island robin / toutouwai
Frost in the valley. I’ve included this to illustrate that on the clearing on the right, called Butlers, the south island robin / toutouwai is now regularly seen. About a doz. were translocated to Aspiring Hut [2 hours walk up the valley] about a decade ago. We’ve known for sometime that they’ve been doing well especially of late, but I’m now very pleased that they’ve migrated this far away from the area they were released, which by-the-way is also by the mouth of the Rob Roy Glacier valley/walk, and quite close to the carpark/trailhead.
Kaka – apparently 5 of were spotted several months ago at the Aspinall Family’s old Mt Aspiring Station Homestead at the mouth of the east branch of the Matukituki river, [donated to Dunstan High School and converted into a comfortable Lodge]. The observer was my friend Eric who has taught school courses there for many many years, and he said it’s the first time he’s seen more than one there. This good news will be due to what is known as the halo effect, DOC’s efforts, and to trapping by my late friend Sam Mcleod who sadly passed away just a few weeks ago. We’re looking forward to knowing more about what is in this valley quite soon – some trips are planned!
Lastly a heads-up about a new project I’m involved with for the Makarora catchment – the Aspiring Biodiversity Trust. I took on the building of the web site >>
The use of 1080 for pest control is supported by a range of conservation and farming organisations, but opponents claim forests fall silent when the poison is dropped, saying this is evidence of harm to native bird communities…
It was back in 2013 that I was introduced to the Matukituki Trust, the brain child of Gillian and Derek Crombie. They’d been climbing annually in Mt Aspiring National Park for many years and had become increasingly disturbed by the diminishing bird life in the West branch of the Matukituki river valley [which hosts the New Zealand Alpine Club’s Aspiring Hut], so they approached the local office of the Dept of Conservation [DOC] and in no time at all formed a partnership with them.
Initially rather than immediately focusing on trapping and getting predator numbers down the Trust adopted DOC’s methodology, which in essence is all about science, and a programme was planned to establish which predators were present, quantifying their food source, and from this planning a strategy, which as it turned out involved the use of the very efficient 1080 poison, followed by an intense trapping programme, which by now equates to 600 traps in the valley.
Now three years on the evidence of our labours is easily evident in the form of a significant increase in various native bird species, thus giving us deep satisfaction and justification of what is by now 1000’s of hours of hard labour, more-often-than-not volunteer based.
DOC staff, a Trust director and volunteers installing funnels which catch beech tree seeds, a significant component of predator diets.
This means of quantifying food, was also augmented by the shooting down of branches of the trees so prescriptive amounts of leaves could be examined and seed counts done. The data then being uploaded to DOC’s database system, and weighed up in relation to other areas, so resources could be utilised efficiently. Photo credit Southern Light
Kea numbers are notoriously hard to know, but in the last two years juvenile numbers have been high from Dec on-wards. A mob of 32 were observed trying to dismantle a Robbie 44 helicopter, just several weeks after 1080 was spread, and this stroke of luck confirmed a long held belief that the valley is a nursery, as they were all juveniles.
This bird and a known banded companion were playing hide’n seek with me a week ago. Photo credit Southern Light
The remainder of the photos below [Photo credits Southern Light] are shots taken while gathering data early on in the programme. Tasks like tracking tunnel installation – about 170 of, and thats mice footprints you can see [other high in number predators were ‘possums’
Pesky ‘possum numbers are now so reduced that the bush is significantly improving in health and “looks”.
On closing some may ask why trapping them for fur/money is not carried out instead of using 1080. Well the answer is simple: as numbers reduce it’s not possible to continue economically, so the trappers bail thus the smaller population grows again very quickly.
In NZ, as opposed to their native Australia, they only need to spend 10 percent of their time eating, and 90 breeding. In Aust. it is the other way round. And of course they then grow larger here
Further reading of interest socially and otherwise:
1080 and science denial: an Our Changing World summit | Our Changing World | Radio New Zealand
We all know the saying: ‘nature abhors a vacuum’. Science denial, though, seems to love an information vacuum and thrives in the absence of fact. Environment and science writer Dave Hansford saw what he thought was an information vacuum around the use of the controversial toxin 1080 to protect New Zealand’s native wildlife, and it motivated him to research and write a book: Protecting Paradise – 1080 and the fight to save New Zealand’s wildlife.
“I think somebody had to [write a book like this],” says Hansford. “There have been a great many books opposing