Fiordland Kiwi Diaries: Season Summary

We’re on the front lines of the Save Our Iconic Kiwi initiative. Our ranger Tim and his team have been studying the population of kiwi at Shy Lake to find out how to best protect them from predators like stoats. 

It’s been a while since our last update and the human world has changed.  But in the wilds of Fiordland, things carry on as usual.  Our native wildlife still go about their lives and many of them still face a struggle for existence against the onslaught of introduced predators. 

Autumn after a beech mast can be a particularly challenging time for species that are threatened by stoats. Stoats have gorged on rodents and their numbers have exploded – but now the beech seed has run out and rodent numbers decline as nature prepares for winter, meaning a lot of hungry stoats running around searching for food. At Shy Lake, I’m sorry to report that we saw the same results this season as in the last two: none of our ten monitored tokoeka chicks survived. 

Once again, stoats were the main culprit. We follow the signal from the small radio transmitter on the chick’s leg, and as we get close we slow down and sneak up to avoid startling the chick if possible.  But when we think we’re on the spot, there’s often no chick to be seen.  That’s when, with a sinking feeling, we start looking for small holes and crevices.  Often there’s some digging involved to recover the sad little pile of feathers, bones and feet where the stoat has stashed the remains of the chick for later.

I said things carry on as usual, but at Shy Lake, that’s no longer the case.  Our long-awaited 1080 drop took place at the end of June, over the peninsulas north and south of Wet Jacket Arm. Covering nearly 40 000 hectares and including the Shy Lake area, this was the most remote mainland aerial predator operation to have taken place so far in New Zealand, and was the culmination of many months of detailed and expert planning. We’re still waiting on some of the results for the post-operation stoat monitoring, which takes place over several weeks. But the results so far are promising, with no stoats and very few rodents so far detected in the control area, even though there were heaps at the pre-op check in May.

There is a downside to this op that we need to face. We were gutted to discover that some of our monitored kea in the area ate the pellets and died. Research has shown that the stoat control will increase kea nesting success to the point where it outweighs this mortality, and it’ll be good for the population overall.  But that’s no consolation to the unlucky ones that died, and it still doesn’t make it sit well.  At the moment, we just don’t have a better alternative for this remote and rugged area, and I’m looking forward to seeing what solutions the next few years may bring. Kea conservation is complex and you can read more in this blog.

So, we think we’ve successfully knocked back the stoat population, but the proof in the pudding will be the upcoming season of kiwi monitoring. Soon I’ll be heading back to Shy Lake to start monitoring this season’s nests, and in a few weeks the first chicks will hatch.  I can’t wait to see them grow, thrive and survive and we’ll be posting more updates.  I really think we can make a difference to the fortunes of kiwi in Fiordland, and we’ve just taken the first big step on an exciting road.

This is the twenty-fifth in a series of posts about Tim’s work, follow the Conservation Blog to keep up to date on his progress.