Fiordland Kiwi Diaries: Five out of five chicks lost

We caught up with Tim, a ranger on the front lines of the Save Our Iconic Kiwi initiative. This is the ninth 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. 

Today I’m flying into Shy Lake with ranger Sanjay and volunteer Vaughn from the Southland Conservation Board.

Vaughn is tasked with collecting signals on the north-west side of the study area in order to check for any new second-clutch nests. None are forthcoming and he drops down a gully to visit our first nesters of the season, Filibuster and Fortuna, on their second nest. Their egg is due to have hatched, and inside the nest Vaughn gets a look at dad Filibuster and, unusually during our visits, mum Fortuna in there also. He can’t see a chick, but he’s pretty confident no big white egg is present. Later we have a look at the footage from the trailcam and are delighted to see that a little chick made its first appearance at the nest entrance six days previously. It’s a good match for our predicted date, based on the point at which the transmitter told us the pair’s activity levels dropped. We would have come in sooner but wet and wild conditions in western Fiordland pushed the trip back a few days.

Fiordland from the helicopter. Photo: Tim/DOC

Meanwhile Sanjay and I check up on Flint and Bones’ wee chick. We follow the signal down into a creek gully and then out of it again around a small bluff. The signal is coming from under the earth and we gently dig up… a pair of legs with a transmitter attached and a few vertebrae. Another classic stoat predation with the legs cached for later. The skin on the legs is pretty decomposed and it looks like it probably happened a while ago. Later the video footage at the nest shows us that the chick did indeed disappear at a little over a week old, only three nights after we fitted the transmitter and the chick started emerging from the nest at night. The nest received several stoat visits after hatching but before our visit.

That makes five out of five chicks so far that haven’t made it past about three weeks old. Most likely all of them were killed by stoats. We’re a long way from a statistically robust answer, but it’s looking pretty serious. The low chick survival doesn’t tally neatly with what appears to be a pretty good density of adult birds at Shy Lake. But kiwi can live for forty or fifty years and as the adults eventually age and die, the pressure on recruitment will tell. We see all over New Zealand that just because a native species population has made it this far, that doesn’t mean it’s safe.

The next day we’re planning some night work to fit a transmitter to Filibuster’s new chick. We spend a wet morning in the hut and then head out to do some track work in the arvo. After dinner I lift my radio aerial to count the transmitter beeps from Calypso, the last signal for the trip. But a tell-tale fast pulse rate indicates a “mortality” signal. This means the transmitter has not moved for 24 hours, which means one of three things: the bird is dead; the transmitter has fallen off; or (rarely) the transmitter has a fault. None of them are great, and with our pick up due the next morning, I pull my boots on to investigate.

Tim spending the morning in the hut doing data entry. Photo: Vaughn Filmer

Half an hour or so later, I’m clambering among the leatherwood several hundred metres downhill. A glint of red reflective tape helps me locate a small brown blob lying in the leaf litter – just a dropped transmitter, and thankfully not a dead bird. But it’s going to make recapturing Calypso next year a lot harder.

En route to stake-out of Filibuster’s nest. Photo: Vaughn Filmer

I’m running late for our chick stake-out and I radio Sanjay and Vaughn to tell them I’ll take a short cut and meet them near the nest. An hour later we rendezvous in the fading light and make our way down to the nest, only to find an empty burrow. We’re half an hour later than planned and we’ve missed the bus. We wait silently in the dark for 15 or 20 minutes, hoping to hear a rustle nearby since the chick is still fairly young and shouldn’t be too far away. But there’s nothing, and we decide our chances are better if we come back in the morning before the flight. The walk back to the bivvy is pleasant in the cool night air and a good sleep awaits.

The morning dawns fine, and with coffee running through the veins, Vaughn and I leave Sanjay to pack up while we head back down to the nest. But the best laid plans of mice and men go oft awry, and there’s still nobody home. I check the camera, but it looks like there hasn’t even been a visit all night. Although relieved we didn’t spend the night staking out the nest for nothing, I’m pretty gutted. Getting transmitters on these chicks is the only way to find out what happens to them, and is the crux of the project and all the work we’ve put in. They won’t respond to played calls like the adults, and once they’re gone from the nest, they’re gone.  This chick is pretty young to have fledged the nest but it appears to have done just that.

Tim tracking Filibuster. Photo: Vaughn Filmer

The helicopter is due soon and Sanjay has to get out for some other work. I’ll probably need to stay in a day or two longer in hopes that the chick turns up. But given that none of the kiwi family are in the nest, and this chick is still quite young, I think it’s worth tracking down Filibuster just in case the chick is with him. Luckily he’s not far away and soon we’re creeping up through patchy scrub, until I see a ball of feathers tucked under a bank and the fronds of a Gahnia bush. I slide a hand underneath to grasp a leg, and as Filibuster struggles a chick tumbles out. Success! Vaughn and I are stoked and we quickly weigh the little cutie, measure the bill and fit a transmitter. Filibuster has run off, so we return the chick to the nearby nest where it’ll be able to reunite with its parents.

We scramble up the gully and arrive jubilant at our pick up point. The helicopter is running a few minutes late and we have time for a quick jump in the lake before being whisked back to civilisation.

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