Fiordland Kiwi Diaries: Monitoring kiwi chicks

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.

We’ve been busy at Shy Lake monitoring this season’s kiwi chicks.  I started the season full of hope, with recent stoat monitoring showing our winter 1080 operation dramatically reduced stoat numbers.  But it’s all about the outcome for the kiwi chicks, so as spring rolled around the first chicks started hatching, we headed into the hills.

The first pair to nest this season was Sinbad Colby and Diamond Raclette.  These guys are great breeders and I can always bank on them to produce a chick from every nest.  In this season where chicks finally have a fighting chance, I was stoked that our best pair were getting stuck into it right away.

A record spring snow dump limited our ability to get around the Shy Lake site, but we were still able to get to this nest, dug in to a bank overlooking Shy Lake itself.  A cautious peek into the nest showed that there was a little ball of feathers tucked under Sinbad Colby.  I was just able to get my fingertips to it and gently extract it from the nest.  We fitted a transmitter to the leg, took a couple of measurements and returned it to the nest where it quickly crawled back under an indignant Sinbad Colby.  Go well, little one.

Over the next few weeks more chicks followed and things were looking promising, with no stoats seen on cameras at nests.  For nearly the first time in this project, I got to meet a chick more than once.  It’s a relief each time to return to a nest and see that the chick is still there safe and sound.

In early November we checked up on our chicks.  Things started well when we tracked down Sinbad Colby’s chick.  We found it tucked in under a log 100 m from the nest, now fully independent with mum and dad nowhere to be seen.  I find it amazing how quickly these seemingly fragile little fluffballs learn to look after themselves and forge their own path, in an environment that I still find challenging even with a suite of modern tech and creature comforts.

Buoyed by this discovery we moved on to T-rex’ nest.  I was expecting this younger chick to still be in the nest but was surprised to find the transmitter signal coming from nearby.  Checking the camera, I couldn’t see any sign of the chick visiting recently and then suddenly there was a picture of a stoat.  This was the first and only one seen on the nest cameras since the 1080 drop, and just an hour earlier was the last video of the chick.  With my heart in my boots I followed the signal to the base of a big old beech tree.  After some searching we had our fears confirmed, as a cavity held a few pieces of the chick.

It was a blow but worse was to come, as over the following days we found the carcasses of two more chicks bearing unmistakeable signs of stoat predation.  Needless to say, this was gutting and the outlook for the remaining chicks seemed bleak.  I’m relieved to say that the following trip a fortnight later didn’t bring any more predations and we still have four chicks alive and well from nine monitored so far this season.

I knew we wouldn’t have 100 % chick survival this season, and in fact, even 50 % survivorship may well be enough to get the population growing, as shown by research in Tongariro forest.  All the same, the recent deaths have been hard for me to accept.  But this is the reality we have to face: we’re still in an exceptional beech mast cycle, with booming stoat numbers across the South Island. 

We’re not the only kiwi project currently experiencing chick losses to stoats.  Ecology is complex, conservation is hard, and we’re up against an amazing predator.  We’re learning all the time about the pest dynamics in this environment.  We’ll continue to follow the chicks still alive at Shy Lake, and in the new year Sinbad Colby and a couple of others will hatch a second clutch, so we don’t yet know what the final results will be.  Several of our chicks have now lived longer than any from the last few years.  It seems like maybe a few stoats were left behind and quickly found the nearby kiwi chicks.  But in other parts of the study site, there’s no indication that stoats are present and I’m optimistic that chicks that have made it this far might have a clear run ahead of them.  If we can get these chicks through, that’s still worlds better than the zero chick survival we saw before predator control, and would represent many more chicks saved across the treatment area.  Just how many chicks survive will tell us how to shape our long term predator programme to get the kiwi population growing and preserve the kiwi call in the nights of Fiordland’s wilds.

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