Fiordland Kiwi Diaries: Back to catching adult kiwi

Department of Conservation —  30/04/2018

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

We’ve come full circle in our first year at Shy Lake: summer has given way to autumn, the breeding season is over and we’re back to catching adult kiwi.

The second egg in Sinbad Colby’s nest, and the last of the season, duly hatched, but sadly it went the same way as the others. Without a way to predict the hatch date of this second egg of the clutch, I missed getting a transmitter on the chick, but three nights after the appearance of the chick, we stop seeing it on the trailcam. Frequent stoat visits to the nest continue and we can be fairly confident that a stoat is responsible for the disappearance. That’s ten out of ten chicks dead.

Shy Lake basin from Celmisia Lodge bivvy.

Shy Lake basin from Celmisia Lodge bivvy

The hot, dry early summer this year, following last year’s cool, wet one, has meant that a strong beech mast is predicted for 2019. With lots of beech seed around next autumn and winter, we can expect a rat plague and with plenty of rats as food, a stoat plague would be likely to follow. However, the predicted high rat numbers should also play into our hands in our efforts to control the stoats and protect kiwi chicks. Our aerial poison drop will mean a lot of dead rats, which in turn means that stoats are more likely to run into one, eat it and succumb themselves.

In the mean time, we continue to work on the “pre-treatment” side of the study we’re doing on kiwi survivorship at Shy Lake. This means following the kiwi through another breeding season and getting a really solid, scientific comparison of how the kiwi do with and without stoat control.

The first thing to do is to try and catch some new pairs. We get off to a flyer when we pay a day visit Myrtle, the female in whose territory the hut sits. We did this a few times last season with no luck, but this time it pays off as we find her in a nice hole under a small beech tree with her mate. We’d already named him “Rusty” and as we fit a transmitter, I’m relieved to think that this season we won’t have to spend several nights wandering round at night trying to track Myrtle in the hope she’ll be on the nest.

Sanjay and Cake the kiwi 📷: Em Oyston.

Sanjay and Cake the kiwi. 📷: Em Oyston

That night we head into some unexplored country to try and call in more new birds. Last year we heard a distant call form this direction but never made it over there. As the sun dips below the horizon, we cross a wide boggy clearing and enter a world of gnarled beech trunks, looping mossy roots and dangling epiphytes. Darkness falls and we wait a little to see if any kiwi call as they get up for the night. Nothing is heard so we play the first call, the sound carrying well in the still air. There’s no response but as we wait quietly, I’m surprised to hear a familiar rustle in the bushes. It’s bound to be a kiwi and we certainly got lucky as they must have been roosting nearby. I play more calls to try and bring it in, and a surge of adrenalin strikes as I hear it approach behind me. I try to turn as quietly as I can, and with the rustles coming very close by, I flick my torch on – only to find that a small bush prevents me netting it as it squirts past my ankles. I drop the net and run at the already retreating male kiwi. They’re fast and he jinks and twists this way and that, but I’m just about gaining on him and about to lunge for a grab when disaster strikes – my headtorch is grabbed by a bush as I pass and suddenly I’m consumed by inky blackness while the kiwi scarpers into the thick scrub. After a minute or two thrashing around in a futile attempt to locate him, we return disconsolately to the caller and set up again: torches off, nets at the ready, control your breathing, wait a minute or two, then play the call.

Luckily and perhaps surprisingly, it works and soon we’re hearing rustles again. This time he seems reluctant to approach closely but instead starts to call, a piercingly loud sound in the still night. He’s only a few metres away and with him busy calling I decide this is the moment to try and get him. I charge across the clearing. I don’t get there fast enough to stop him turning to run and a short but frantic chase ensues, but this time I’m lucky and manage to gather him up.

Ranger Tim with Flint.

Ranger Tim with Flint

He drops a lot of feathers from his legs and lower abdomen, a behaviour known as “stress moulting”. It’s a bit worrying and so we skip a few of the less important measurements so we can let him go a bit sooner. He scampers off sporting his new transmitter. That’s the last we’ll see of him tonight. Meanwhile his mate has given a couple of calls nearby, so we set up again and try to call her in. She approaches a bit but won’t come close. She hangs back and calls, a harsh guttural roar. As we focus on the sound, trying to gauge distance, we’re startled to hear a shrieking whistle right beside us. The male, supposedly all stressed out and hiding under a bush hundreds of metres away, is back in our midst and keen for round two! With the pressure off to catch him, it’s amazing to enjoy hearing him call right next to us, an electrifyingly wild sound. It does make things pretty tricky trying to listen for his mate though, as we try to keep track of whether the occasional rustles are made by the male or the female. Eventually I hear what I think is a new rustle, turn on my torch and run at it – only to pull up immediately as the reflectors on the transmitter catch my torch beam. The male beat my echolocation and I’m chasing the wrong bird. This latest disturbance is enough for his lady too – she was never as close, but pegs it into the undergrowth and we don’t hear from either of them again. Ranger Stef christens the male “Nuts” and the female “Bolts” to reflect their behaviour.

We give up on Bolts and move on, and we get another pair that night to complete a fantastic day. But from then on it gets much harder: individual kiwi vary widely in how strongly they respond to the calls we play, and we’ve already got the most aggressive ones in our work area. To add to that, some of the uncaught ones have learned that things aren’t always what they seem when kiwi start calling in your territory. They wisely (but frustratingly for us) stay quiet or keep back in the thick scrub, where we have no hope of catching them in the dark. The result is a few nights trudging around the basin, playing calls that get no response and coming home about 5 am with our tails between our legs. This is compounded by a very wet autumn in Fiordland. When it’s raining the kiwi don’t respond to calls much, and anyway it’s very hard to hear kiwi moving in the dripping forest, so we can’t do the work without half-decent weather. We need at least a couple of workable nights to justify the expense of the helicopter in, but we end up with only half of the catching time I’d hoped for. The catching season wraps up in mid May, to avoid disturbance to the birds as they gear up to nesting from June, so we’ll have to make it up next year.

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

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