Feral Peril

[a stoat trap along NZ's Kepler Track. Click on the image and see if you can see the deceased stoat inside!]


[A cautionary tale from across the Tasman Sea]

It is not an altogether pleasant experience to be woken by mice scurrying over your face. The unpleasantness increases when the wider implications of a mouse plague in remote New Zealand are understood.

It’s spring 2006, and we are on our first serious tramp in the South Island of New Zealand. Our overnight stay in Aspiring Hut is very early in the season, just days after the hut has been fully opened.

2006 is a beech mast year – meaning that the various species of southern beech that dominate the forests of New Zealand are seeding prolifically. That’s good for the future of these beautiful forests, so reminiscent of Tasmania’s myrtle forests (to which they are related). But it’s also good for anything that will eat the seeds, and this year that’s conjured up a vast multitude of mice.

In, under and around Aspiring Hut hordes of mice have seen out the winter. With the thaw and the longer days they’re breeding and feeding at a frantic rate. Hence the early morning tip-toeing across my beard. Later, when we walk the Routeburn Track, the forest floor is alive with mice. In my peripheral vision the forest floor seems to undulate as mice scurry to hide from the passing bipedal “giants”. Afterwards they will return to the beech feast.

I used to count Australia the world champion in the field of introduced pest species. Eric Rolls’ 1969 classic book They All Ran Wild examines the lamentable record of our inadvertant rape and pillage of the environment via introduced furry, hard-hoofed, leafy and prickly living things.

“Inadvertant” may be too kind, given that Australia had acclimatisation societies in the 19^th century that aimed specifically and deliberately to introduce and establish plants and animals in this country. Their goal was partly economic, but they were also trying to make this “new world” look and feel more like the old. The founder of the Victorian Acclimatisation Society, Edward Wilson, went so far as to state “if it lives, we want it”.

But after my 2006 experience, and bearing in mind the spirit of trans-Tasman rivalry, I have to concede that New Zealand may be even more over-run by feral species than we are. And not just by mice. The food chain doesn’t end with the small rodents. Rats eat mice, and when mice are scarce then birds and bird eggs will do fine. In turn well-fed rats are fine food for mustelid predators such as stoats.

And when stoats can’t get rat? Well, while walking the Kepler Track in the mountains west of Te Anau, I found the sad answer. At the time I was struggling to find my walking rhythm. At such times I resort to tricks that help distract my mind and body. On the Kepler I used a series of pink triangles nailed at intervals along the track as both a distraction and a crude tally of my progress.

Of course the tags also piqued my curiosity. Hitler had sewn pink triangles onto the clothes of male homosexual prisoners. In this case the tags marked the location of stoat traps. And I learned that what stoats turn to when rats become scarce is birds. And what better than the fat and flightless takahe.

So the intensive trapping effort along the Kepler Track was aimed specifically at giving the dwindling population of takahe in the nearby Murchison Mountains a chance at increasing its perilous grip on what was once its stronghold.

The takahe (Porphyrio hochstetteri) is a large, strikingly-coloured bird believed to be descended from wind-blown Australian birds (similar to swamp-hens). Several million years in isolation has left them flightless and large - they weigh around 3kg. That’s fine in an environment virtually free of carnivorous predators, but disastrous when killing machines such as stoats are added to the mix.

By the end of the 19^th century, takahe were believed extinct. Then in 1948 a small number was found in the mountains across the lake from where we were walking. After huge breeding and trapping efforts, the total population is currently around 220 individual birds.

By the end of the 3 day walk I had counted over 120 trap markers. The traps themselves were mostly well hidden. However near the end of the walk I wandered off track near a marker to see what a trap looked like. Built to be accessible to mustelids rather than men, getting close to the wood and mesh box was difficult.

I lined my camera up near the cage and shot off a speculative photo – without actually being able to see through the view finder. To my surprise, weeks later, I discovered that I had photographed a dead stoat inside the trap? It was only after zooming in on the image that I made out the twisted and grisled stoat corpse (see image above).

On learning from Department of Conservation (DoC) rangers a little more of the story, my curiosity about stoats soon turned to anger. They were introduced to New Zealand in the 1880s in an attempt to keep rabbit numbers low. At the time there was strong scientific and political opposition, as even then the likely effects on non-target species was predicted. However the powerful farming lobby won the day, and New Zealand’s fauna – and its tax payers – have been paying a high price ever since.

Despite a number of similarly sad New Zealand stories, a Tasmanian like myself steers well clear of the high horse. The extinction of the thylacine here is tragedy enough; the “export” of Tasmanian possums to New Zealand terrible. But the deliberate 21^st century introduction of the European fox into the world’s only stronghold of carnivorous marsupials? Take me to the hair shirt and flagellation whip!

No Such Thing As Bad Weather

[photo: high in the Kepler Mountains, New Zealand]

[more thoughts on walking and weather]

My colleague and friend, Cathie, has waged a war of words with terms like “bad weather”. One of her favourite quotes is from Joseph Wood Krutch:

The good thing about the country is . . . that we don’t have any bad weather at all – only a number of different kinds of good.

And Cathie’s right. The wild parts of Tasmania, New Zealand, Alaska and places like them would not look as they do; would not have the same plants and animals; wouldn’t even have the same topography, were it not for the weather. Mountains, forests and fiords come at a climatological cost.

That’s not to say that we always want to be out in the wilds when it’s blowing a gale and sleeting or snowing. But we recognise that such weather in an inherent part of the wild country that is so attractive to walkers. We adapt to the weather, not the other way around. One way to do that is to have good all weather gear, and/or to develop a positive duck-like attitude. Another is to have the flexibility to walk when the weather is expected to be fine. In that regard long-range internet weather forecasts are a great thing. I use them all the time, and they have made a big difference to my walking. For a start they can give warning of extreme conditions that are best avoided, although some familiarity with meteorology and lots of experience of local conditions is still important.

My ideal scenario in Tasmania is to start a walk on the tail-end of a cold front, especially when it looks as though it will be followed by a large, slow-moving high pressure system. This will usually bring calmer conditions, cool nights, and clear days. So while you may start the walk in cloudy or rainy conditions, the promise is that the high will come to the rescue. If it does the result will be a few days of clear weather when you’re actually among the mountains. With the exception of masochists and wilderness photographers in search of “artist’s light”, this is bliss for a bushwalker. And occasionally it does work out that way, although the weather gods often have the last laugh, and a bushwalker’s best-laid plans go oft astray. In the end we have to accept that we don’t control the weather, and making the most of it bears more fruit than shaking a fist at it.

Four days on New Zealand’s Kepler Track, west of Te Anau in Fiordland National Park, proved a good example. In Fiordland you can wait a long time for a forecast indicating a spell of clear weather. This part of the world measures its annual rainfall in metres, not millimetres, and the roaring forties bite particularly hard around here. But in planning to walk the Kepler Track, I did have some flexibility with dates. So I sat on the long-range forecasts for days trying to pick a four day period that might translate into clear weather for at least the day spent in the alpine section, at around 1400m. As I read the forecasts, I prevaricated, planned, replanned, and prevaricated again. Yes, it was spring, but the procession of cold and/or wet weather systems seemed interminable. And not knowing how this would play out on local weather patterns made it hard to commit. I wanted to pay due respect to the potential for wild weather up in those mountains. But eventually taking both local advice and the plunge, I booked the walk. We chose to do the loop walk in the less usual clockwise direction. Forecasts indicated clearer weather for day 3, the alpine day. If we went in the other direction, we’d be up there on day 2, which looked dire.

It turned out my choice was both right and wrong. Wrong because it snowed on and off throughout our entire alpine day. And right because the day before did turn out to be a savage, wet and windy day. Walkers we met at the walk’s half-way point, the Iris Burn Hut, told us they’d been literally blown over by gale-force winds. Some had even lost equipment, blown off the mountain by the wind. And they’d seen almost nothing through the rain and flying cloud in the head-down hurry to get off the mountain. And our snowy day? Well that was the other part of being wrong. Had I been invited to walk for 8 hours through sleet and snow – more than half of it steeply up hill – I probably would have declined. Yet it turned out to be one of the most brilliant days of walking I’ll ever experience.