Fiordland Kiwi Diaries: Our second season of nest monitoring

We caught up with Tim, a ranger on the front lines of the Save Our Iconic Kiwi initiative. This is the fifteenth in a series following the work he’s doing to save the Fiordland tokoeka (kiwi). 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. They have captured a number of kiwi and put transmitters on them, and are now monitoring them through the breeding season to find out how well the adults and chicks survive without pest control. 

As September rolls around, we begin our second season of nest monitoring for the southern Fiordland tokoeka at Shy Lake. After several months away, it’s nice to be back among the sheer faces, lush forest and golden tussock, the sound of running water ever-present.

Looking down towards Breaksea Sound. 📷: Bridget Railton

Prints in the snow. 📷: Bridget Railton

The smart software in our adult kiwi’s transmitters has told us who is already nesting and who isn’t. Incubating birds spend less time moving around, and the transmitter can sense the activity level and translate it into a pattern of beeps. Last year we counted thousands of beeps to get the raw data that we needed to determine the onset of nesting, and so predict a hatch date for the egg. This year we’re using even smarter software, developed for the Haast tokoeka a few hundred kilometres up the way. The transmitters can detect the drop in activity that heralds the arrival of an egg, and can then tell a ranger on the ground or even an aircraft overhead how many days it is since the male started incubation. Clever stuff, and saves us a lot of expensive trips to our field site in the early part of the season.

Armed with our list of nesting pairs, rangers Anne, Jenny and myself are dropped on hillsides around the study area and start radio tracking. It’s an exciting time as we sweep our aerials back and forth, seeking for the strongest signal that points the way to a kiwi, snug on his nest. One of last year’s early nesters, Pegleg, is again leading the charge, but I’m surprised to find he’s chosen a nest just a couple of metres from a creek. That chick had better be careful not to fall in – “misadventures” like this can be a significant cause of chick mortality in some other kiwi projects. I install a trailcam to monitor for predator visits and move on.

Tracking signals in the snow. 📷: Peta Carey

I have mixed emotions about this season’s monitoring. It’s amazing to work with kiwi, out in the Fiordland wilderness, but in the back of my mind are last season’s disastrous results, when every chick we monitored died within a few weeks. At the same time, there is hope that this year one or two might make it, not least because at our annual transmitter change in March, we found that a couple of our adult’ bills had grown, indicating that they’re still young. So although I know better than to get too attached to these chicks, it’s hard to not to get my hopes up. The main thing that motivates me is the knowledge that what we’re working for is kiwi conservation on a grand scale: the saving of hundreds of chicks in next year’s 1080 operation, and then moving our operations to conserve the population in other areas of Fiordland in future seasons.

Returning home on dusk. 📷: Tim Raemaekers

A few weeks later we’re back for the first hatches of the season, and to check up on the camera footage. Unfortunately the cameras tell an all-too-familiar tale: once again, over 80 % of our nests have had stoats visiting. As before, the stoat visits occur randomly in relation to human presence at the nest – sometimes it’s a day or two after our visit, sometimes it’s weeks later. I can rest easy that it’s not just us humans leading stoats to the nest; and common sense would remember that kiwi smell at least as strong as we do and are tracking to and from the nest multiple times a day, instead of once every few weeks. Possums and weka are also making their presence felt, but the kiwi are defending their patch vigorously. Reviewing footage from Commando’s nest in the hut, I spill my tea when I see Commando not only chase a marauding weka from the nest, but grab it with his bill and administer a good kicking! The weka is pretty staunch too though, and keeps returning to the nest, waiting for an opportunity.

Elsewhere they’re more successful: a week or so after our visit, Gulliver kiwi and his mate unexpectedly stop showing up at their nest. A couple of days later, a weka enters the unattended burrow and leaves again with egg hanging off its beak; later it removes the eggshell. By the time I get there next, there’s not much to see. There was a bit of stoat activity at this nest and I speculate that maybe the egg got stomped by one of the kiwi in the process of chasing off the stoat; but we’ll never know for sure.

There’s better news across the valley, where the first chick of the season has hatched at Pegleg’s nest. I marvel all over again at the ball of fluff, bright eyes and plump pink feet that I hold in my hand. Ranger Sanjay and I fit a tiny transmitter and return it to the nest. Take care little one, and steer clear of that creek!

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