Drawing blood from a grumpy parrot is no small feat. But Andrew Digby and Deidre Vercoe, who lead New Zealand's kakapo recovery program, are well-versed in the maneuvers required to keep the heavy birds still.

With one hand around both clawed feet and the other around the bird's neck to grip its beak, one holds the kakapo while the other slowly inserts a needle to draw a drop of blood into a tiny syringe.

All the while both of them murmur and hum gently to the bird, much as you would to a baby.

Drawing blood from kakapo parrots is tricky business

There are only 123 kakapo left in the world. These bizarre flightless, nocturnal and sweet-smelling parrots are so rare that each has its own name to humans.

And every one of them carries a microchip under his or her skin, along with a transmitter on his or her back. Their sex life is arguably the most closely monitored of any endangered species. This includes sperm tests, artificial insemination - and now, thanks to the blood samples, genome sequencing.

The team's hope is that with better genetic knowledge, they will be able to avoid inbreeding, zoom in on genes that might predispose some birds to disease, and halt any further decrease in genetic diversity.

Infertility eroding the species

Most kakapo live on Codfish Island, a predator-free sanctuary off the southernmost tip of New Zealand. Two other tiny islands are home to smaller groups.

On all three, 2016 was a record breeding season - the best since New Zealand's Department of Conservation began managing and monitoring kakapo 25 years ago. The birds produced more than 100 eggs - but disappointingly, more than half of them were infertile.

Bizarre bird: The flightless kakapo is only active at night

Infertility is not a surprising issue in an inbred population, said Digby. But for kakapo it seems higher than one would expect. "We're hoping that we'll get markers that we can use to find out if there is a genetic basis for the infertility we see," he told DW.

Kakapo don't exactly help themselves. They are the only parrot in the world with a mating ritual in which a male sits in one place on the forest floor at night, scraping a shallow bowl across the ground and emitting a low-frequency boom that travels across long distances. If he's lucky, a female might consider his call attractive enough to mate with him.

Berry good food

What's more, kakapo only breed when a particular native tree - the rimu - produces a lot of berries. This fruiting seasons only happens every two to four years. While adult kakapo do just fine without the rimu fruit, it seems to be an essential ingredient in the chicks' diet.

During the breeding season, female kakapo will climb several meters up a tree to collect berries for themselves and for their young.

"Zephyr 2" was the final chick to successfully hatch in the 2016 kakapo breeding season

The small orange rimu berry may hold another clue to kakapo fertility. "We've learned in the past that kakapo have very low levels of vitamin D," said Digby. "But rimu fruit is a vitamin D super food," he continued.

Adult kakapo actually feed their chicks about 500 grams (about 17 ounces) of ripe rimu fruit a night, which gives each chick about 30 times the human recommended daily amount of vitamin D.

"There's this paradox that adults have very low levels [of vitamin D], but they are feeding the chicks this extremely vitamin D-rich diet," Digby explained.

Predator-free evolution

When New Zealand separated from the ancient southern supercontinent Gondwana about 80 million years ago, it carried a precious cargo of birds, reptiles and insects - but no predatory mammals. Kakapo were plentiful throughout the archipelago.

Their spiral toward extinction began with the arrival of humans. Polynesians came some 700 years ago with rats in tow. When Europeans colonized New Zealand, they brought an entourage of ship rats, cats and stoats.

Kakapo chicks need a diet rich in vitamin D

By the 1970s, the kakapo was thought to be extinct - but two remnant populations were eventually discovered. One, in Fiordland, included only males.

Just one of the Fiordland males, a bird called Richard Henry after a pioneering New Zealand conservationist, has passed on his genes. His three offspring, Sinbad, Gulliver and Kuia now play a crucial role in helping rebuild the population.

Intervention for the sake of conservation

During breeding seasons, conservation teams descend on each of the kakapo islands to give the birds a helping hand. Deidre Vercoe says the team employs a suite of remote-sensing technologies to keep watch over just about everything, from the precise period of time a mother leaves her nest to the exact identity of birds involved in mating.

Advanced tracking technology allows conservationists to know virtually everything about the birds' reproduction

Should a female mate with a genetically unwanted suitor, the team will intervene and inseminate her artificially. In a process common in birds, sperm from the last mating is usually more successful and, as a bonus, multiple matings also boost overall fertility.

The next stage of management is at the nest site. Any clutches that are bigger than one fertile egg are divided and "fostered" out to other birds with infertile eggs. In this way, each of the chicks has a better chance of survival. According to Vercoe, genome sequencing will make this already intensive approach an even more precise science.

Asked how long it might take for kakapo to be safe from extinction, she said she'd like to get to a point where there are three large populations, possibly with 500 birds or more.

"When we started this program, we had 51 old birds. But now we have quite a large proportion of young birds with a long lifespan ahead of them - so we're on the right track," Vercoe said.