It’s unlikely that a female kākāpō agonises over her weight.

Fortunately, however, there are a group of humans who do that for her.

It’s been a bumper breeding season for the critically endangered kākāpō, on the predator-free islands of Whenua Hou/Codfish Island off the coast of Stewart Island, and Pukenui/Anchor Island in Fiordland’s Dusky Sound.

It’s shaping up to be the biggest boost to the critically endangered population on record. As of March 1, 217 eggs had been laid, and 48 chicks had hatched – that’s one more than the record set in 2016.

The success of this year’s breeding season, in a rimu mast year, will in a large part come down to the work of DOC’s Kākāpō Recovery Programme. Scientists, rangers and volunteers are working around the clock to protect the precious nocturnal flightless parrot.

In one of the unusual things about the kākāpō, the female’s weight can determine the sex of her offspring. An overweight bird is more likely to produce male chicks (kākāpō can pile on 1kg of fat leading into a breeding season).

So it’s up to a band of enthusiastic volunteers to make sure the birds are served up the right amount of sustenance daily – for their health, the wellbeing of their offspring, and the gender balance of the kākāpō population.

It’s crucial to get the sex ratio right. It’s DOC’s vision to have at least 150 healthy adult female kākāpō.

Kākāpō in the southern islands only breed when rimu trees put out masses of fruit – a mast year – which happens every two to four years.

“The birds are absolutely amazing at predicting a mast year,” says DOC’s kākāpō advocacy ranger, Bronwyn Jeynes. “Somehow they know before we know; they start gearing up for it before there’s even fruit on the trees.”

This year the breeding season began early on Pukenui and Whenua Hou, and 49 of the 50 female kākāpō on the islands mated.

In a breeding year, DOC need volunteers to help the recovery team with their supplementary feed-out programme.

This summer two Blake Ambassadors went into the Fiordland wilderness to help. University students Miriam Clark and Sarah Manktelow spent two weeks on Anchor Island managing the individual diets of each kākāpō.

Every day they prepared a different food bag for each bird – pellets weighed out depending on the bird’s weight. Some birds, especially females, also required a flaxseed oil supplement to help enhance egg formation.

The two volunteers would then walk on a loop around the island to the kākāpō feed stations. “It was hard yakka carrying heavy packs up steep hills,” Clark says. “We had every kind of weather thrown at us too.

“Most of the feed-out stations on Anchor Island are smart hoppers, which detect which bird is at the feed station and will only unlock if it’s the designated bird’s feeder. That way the amount of food eaten can be recorded accurately and the leftover food can be taken back to base to be analysed.”

Electronic scales beneath each hopper, and a data logger, record the weight of each bird who feeds there. That data then helps with the food rationing plan.

The feed-out team were made very aware of the risk of disease to the fragile kākāpō population, so they would also clean the feed station with an antibacterial solution each day.

“Our feed-out programme is very rigidly managed,” Jeynes explains. “Managing the birds’ weight makes a huge difference to the population.”

“The fact we have a weight line for the birds is testament to how much work and research has been done into the species.”

Clark and Manktelow were also involved in finding the kākāpō nests – in hollow trees, or caves made by rocks and roots – and helping with the egg collection.

Eggs are removed from nests to be incubated back at the DOC base, reducing the chance of accidents and increasing the survival rate.

This year, DOC is trialling a 3D-printed “smart egg” – left in the nest emitting life-like sounds so the kākāpō mum will start preparing for a new chick. Once hatched, and healthy, the chicks are returned to the nests.

Because this breeding season began so early, DOC rangers have blocked off many of the nests, encouraging the female kākāpō to go out and mate again, and produce a second clutch of eggs.

“We’re pushing for them to produce as many eggs as possible,” says Jeynes. “Right now that’s the most important thing for these guys – getting the number of kākāpō up.”

The female bird that Jeynes has adopted, Waikawa, is a good example. She had three chicks in her first clutch (including the first kākāpō chick of the season born on January 30), and has laid four more eggs a second time around.

In the last breeding year, 2016, Waikawa was the youngest female kākāpō to breed, but flash flooding on Anchor Island wiped out her nest. Only one of her four chicks survived to fledge.

Although the islands are mammalian pest free, Clark and Manktelow were also involved in checking a trapline in Luncheon Cove.

For Clark, the volunteer experience was “incredible… it made me realise that it’s never too late to start doing our bit in preserving New Zealand’s conservation so that our future generations can experience them too,”she says.

“The most inspiring thing was seeing what the DOC rangers go through, what they put on the line, for those birds. The sleep loss they endured – every night going out to find nests, set up nest camps and collect eggs.

“Their tenacity is incredible. They are the essence of conservation in New Zealand.”

Clark, who grew up on the banks of the Hurunui River in north Canterbury, has been involved in a raft of environmental projects since she was a young teenager.

At Hurunui College, Clark was a senior leader in the project to return Nina Valley in the Lewis Pass to its pre-European status. Inspired by attending the Sir Peter Blake Trust’s YELF student forum in 2016, she then set up her own conservation project, Projekt Pukeko – trapping predators to restore the bird population in her local swamp.

She was also one of the young Blake expeditioners who visited the Kermadec Islands in 2018.

After a gap year spent exploring the South Island’s mountains, Clark is now at Canterbury University studying commerce, majoring in management.

Both Clark and Manktelow (who’s studying ecology, marine science and music at the University of Otago) want to continue helping the kākāpō.

“Sarah and I want to come back as a cook or volunteer. We’d like to go to Whenua Hou next time and experience the different vibe,” she says.

Jeynes welcomes them back with open arms, and encourages new volunteers – two for the feed-out and one cook every fortnight on each island during the breeding season from November to July.

“We need hands on deck for the sheer scale of work that has to be done. Kākāpō are so rare and special to New Zealand, so having volunteer positions give the opportunity for people to see the species. People don’t care about something they can’t see,” she says.

“It’s so important for the long-term future of the bird. People need to understand why what we’re doing is so crucial for the kākāpō’s survival.”

Photo: Kākāpō image: Dr. Andrew Digby/DOC