Fiordland Kiwi Diaries: Stoat predation and beech-seed funnels

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

You can find the first post here, and the entire series here.

The gorgeous early summer continues down south, and it’s time to escape the computer again to check up on the southern Fiordland tokoeka at Shy Lake.

Shy Lake and Celmisia Lodge. Photo: Vaughn Filmer

Our trip starts the usual way – ranger Hamish and I are dropped two or three hours’ walk from the bivvy and begin by collecting radio signals from the kiwi in the area.  An hour of counting beeps reveals nothing too surprising: Bones and Flint still have low activity levels, indicating incubation of an egg or brooding of a chick.  Meanwhile Cake and Candles’ activity levels have climbed, which is to be expected as their chick should have fledged the nest by now.  We set off in the sunshine to check out Bones’ nest, which will hopefully have a new chick awaiting us.  We find Bones on the nest and gently encourage him to stand up with a leafy branch.  A gleam of white shows us that the egg has not hatched, so we back off and move on to check up on Muffin, the chick of Cake and Candles from a few weeks ago.

Muffin’s legs with transmitter still attached. Photo: Tim/DOC

The signal points to an area not too far from the nest, and we home in on a rotten log.  But an investigation of the holes reveals no chick, and ominously, we have to do a bit of digging of a rather small, rocky hole.  It’s as we feared: just a pair of legs with a transmitter attached.  It’s classic stoat behaviour to eat out the head and guts and stash the legs for later and I don’t bother sending this one away for post mortem or genetic analysis.  Checking the trailcam footage later, we see that the chick left the nest three days after our last visit, at the ripe old age of sixteen days, and never returned.

Things don’t get much better at CamemBert and BrieAnne’s nest – they have abandoned it, as we expected since they were way past the projected hatch date.  Hamish digs the nest up, which takes a fair while as it’s about 2 metres long and at least half a metre down.  Buried in the floor of the nesting chamber he finds the cold egg, which shows no sign of development – either infertile or failed incubation.

Hoping to get some runs on the board, we carry on until we reach the track down through the bluffs and across the main creek that feeds Shy Lake.  Half an hour’s bush bash up the hill on the other side sees us pop out onto some flats, shedding their winter yellow-brown in favour of a vibrant green.  We’re here to track Gulliver, a male on what should be a new nest.  A little later we find him sitting high and dry on a cosy nest in the base of a large hollow log.

Next day we have some seed funnels to install.  The main purpose of our work at Shy Lake is to test the response of kiwi populations in the beech forest ecosystem that forms most of their Fiordland habitat.  We need to be able to measure the intensity of a beech mast (heavy fruiting) year, and we do that with a big plastic funnel sitting on some waratahs under the beech trees.  At the bottom of the funnel is an ordinary ladies’ stocking to collect the seed that falls.  In a few months the stockings will be sent away for the seed to be meticulously counted.

Installing a seed funnel. Photo: Vaughn Filmer

When we’ve installed as many seed funnels as we can easily carry at once, it’s back to the kiwi.  Unfortunately it’s more bad news.  The transmitter from T-rex’ chick is stashed way inside the bole of a beech tree.  After an hour of sawing and digging I still can’t get at it but it’s likely to be dead as it couldn’t have climbed out of the hole in question.

Stoat at T-rex’s nest, caught on trail-cam

Next week I’m back with a chainsaw to have another go, but again am defeated by the tangle of wood and rock.  It’s highly likely to have been eaten and then stashed there by a stoat, but there’s just a chance that the chick fell down the hole, couldn’t get out and then crawled out of reach to starve, the poor wee thing.

Across the valley a nice surprise awaits, as a visit to Bones and Flint’s nest reveals another cute wee chick, the fifth of the season.  It arrived 11 days later than my predicted hatch date, I got that one pretty wrong.  But no harm done and a transmitter is fitted.  Ranger Bex and I carry on to find that Pegleg and Sinbad Colby have both re-nested, and both used the same nest burrows as for their first clutch.  Hopefully it’s second time lucky for Pegleg, whose first egg just failed to hatch, as his is one of the few nests not to have been found by a stoat yet.  Unfortunately for Sinbad Colby, with so many stoat visits to that nest site, I can’t see a second chick of the season standing much more chance than little Waimarie did.

There’s disappointment the next day when I visit Rusty and Myrtle’s nest, acquired last month after 11 hours of night work, only to find no kiwi and no egg.  The camera footage seems good, and there are lots of stoat visits, but I can’t tell what happened to the egg.  I suspect it’s been rolled out of the nest by a stoat, but a search downhill reveals nothing to me.

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

Kea at the bivvy. Photo: Vaughn Filmer