How climate change threatens New Zealand’s kiwis

kiwi
North Island Brown Kiwi of northern New Zealand. Photo by Eric Isselee/Shutterstock

This story originally appeared in Newsroom of New Zealand. It is republished here as part of BirdWatching’s partnership with Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

It was not what the farmer expected to find in the paddock. Curled in a ball in the hot sun was a normally nocturnal kiwi chick.

At the top of New Zealand, Northland was experiencing another drought. Desperate for water and unable to probe the dry, hardened forest floor for moisture-rich insects, young kiwi were venturing into exposed paddocks to find food.

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It’s a problem Whangarei Native Bird Recovery Centre’s Robert Webb has seen in recent dry summers and it’s unlikely to stop. Climate change predictions say in the coming years the region will spend double the time in drought as it does now.

Kiwi get much of their water from the insects they eat. With the forest floors rock hard, kiwi are attracted to the dew on farm paddocks. 

“The kiwi just keep walking, walking, walking and all of a sudden daylight comes along and they’re way out in the middle of a paddock. Then of course the heat of the day comes and dehydrates them and they die.”

As well as in paddocks Webb said kiwi have been found raiding cat bowls and attempting to drink water dripping from parked machinery. 

“Of course, if it’s got anti-freeze in it, it will kill them.”

Sometimes they’ll climb into old bathtubs repurposed as stock troughs, or water tanks or bores. Their claws are useless on slippery sides and once in there’s no way out. They’re found drowned, with toes worn out from scratching the sides to escape.

Over a three-week period eight dehydrated kiwi were brought to the recovery center, mostly by farmers investigating an odd “blob” spotted in the paddock when moving stock. Webb, his wife Robyn and volunteers nursed them back to health with injections of fluids and glucose. In the severe drought of 2010 seven dead birds were found.

When droughts come kiwi chicks in particular struggle. Adult kiwi are around two to three kg. The chicks coming into the recovery center weigh 300 to 400 grams. 

“They’re little wee fellas, they’re tiny. You can cup them in both hands and they snuggle in and you’ve got a ball of fluff sitting in your hands,” said Webb.

Adult kiwi are stronger making foraging, even during droughts when the ground is rock hard, easier.

“They’re powerful birds with their claws. They’re rake open an old rotten bit of log and find huhu grubs and things like that. A little kiwi can’t do that.”

Niwa predictions for the region is bad news for hungry kiwi. 

Based on the current trajectory and sticking with business as usual with no emission reductions during the 21st century, time spent in drought, where the ground gets too hard for kiwi to probe will double.

There will be 74 more days per year where the temperature is over 25C. Summers will be up to 3.3C hotter. In spring some areas will get 20 percent less rain. 

Latest figures from New Zealand’s Greenhouse Gas Inventory show in 2017, gross emissions rose 2.2 percent. From 1990 to 2017 there’s been a net increase of 65 percent.

Backyard Kiwi project manager Todd Hamilton said the population can cope with the occasional drought.

“You might lose a generation of chicks. That’s not the end of the world, it happens in nature, but if it happens too much you’re in trouble.”

Drought also impacts the next year’s breeding. 

“It’s all about being fat and happy and having kids. The males and females both need to feed up, usually in late summer and autumn to start their breeding season. It was the driest year on record for us for the first six months of the year and our breeding was six weeks late.”

The late start meant only one breeding instead of two. This effect is a post drought double-whammy. Chicks born into drought die and fewer chicks are born the following year. 

Hamilton said in his area in the Whangarei Heads the kiwi population has grown from 80 in 2001 to around 900. He puts success down to education — it’s no longer socially acceptable to have dogs off leads — and predator control.

Stoats kill kiwi chicks and when the local stoats got too clever for the traps 1080 (a rodenticide) was used. This kills rats and stoats feasting on the poisoned rat carcasses are also poisoned. 

The common bush tail possum, an Australian species that is not native to New Zealand. Photo by Brisbane City Council, CC BY 2.0

There’s a drought related bonus to all this. Leaf-chewing possums are also killed by 1080. 

“Our forests are healthier, they grow more leaves, have more leaf litter and everything spirals upwards.”

It’s not just drought which affects whether kiwi can get to food. New Zealand’s history of introducing species complicates and exacerbates some effects of climate change.

Possums place an additional stress on drought-stressed trees. With canopies stripped by possums and with roots thirsty for water, they die. The canopy vacuum left allows sunlight to stream onto the normally shady forest floor, drying and hardening it.

Forest & Bird’s northern advocate Dean Baigent-Mercer said the collapse of Northland’s forests has been a catastrophe in slow motion.

“People don’t really know what normal is and how healthy it should be and loud, and vivid, vivid greens. I look across forest canopies now and often there’s greys. The greys have become quite normal because it’s happened over lifetimes.”

The greys are the skeletons of dead trees. As well as letting the sun dry out the forest floor, the dead trees aren’t dropping all important leaves because they’ve ended up in possums’ stomachs. 

Without the possums dropped leaves would have become leaf litter, insulation for the forest floor and home to all manner of insect life. A good leaf litter is a buffet to foraging kiwi.

With possums present in Northland since the 1960s the leaf litter has progressively got thinner.

“Having moisture in the ground is really, really important. Obviously they’re flightless. They can probe down quite deep and the need to get bugs through the leaf litter and down into the worm layers.”

Last year the Department of Conservation dropped 1080 on the Russell Forest and Rakaumangamanga/Cape Brett for the first time in decades. Possum numbers dropped to a fifth of what they had been in Russell Forest, and a 10th of previous levels in Rakaumangamanga/Cape Brett.

These two areas are just a small part of Northland’s total forest cover. 

“Any native forest in Northland that doesn’t have pest control is collapsing. It doesn’t matter if it’s Department of Conservation managed land, private land or Māori land. If there’s not pest control going on that target possums, rats, deer, feral cats and stoats, they’re dying. Not only the trees but the bird life.”

Robert Webb and his wife have been rescuing native birds for 35 years. He said it’s something you either need to be dedicated to do or be “bloody silly”.

“For me the birds were here before man was here and I personally didn’t think the wild birds were being looked after enough. We’ve crashed in on their habitats, built houses and put up power lines and cars and windows and god knows what else. All these things are hurting the birds.”

Each year about 1300 birds are brought to the centre ranging from albatross to kiwi chicks. These are rehabilitated and released back into the wild. 

“I’m just hoping we’re not going to have a stinking hot summer because it’s going to play havoc on the kiwi chicks.”

If business as usual continues, climate change is likely to bring more stinking hot summers to Northland. 

Curious birds that can’t take flight but sure can run

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Farah Hancock

Farah Hancock is a Newsroom reporter based in Auckland who writes on conservation, technology, and health.

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