“We Also Tried Remote Control Cars Dressed As Females”: How Scientists Took On Rare Kākāpō Artificial Insemination

Kākāpō (Strigops habroptilus) are one of New Zealand’s many flightless birds, and considered the most endangered. Never having had to deal with mammals (bats aside) until humans arrived 700 years ago, they were completely unprepared for both us and the animals that came with us, causing a population crash that bottomed out at just 51 birds in the 1990s. They now survive only on three sanctuary islands, which have been cleared of threats like rats.

That, however, has not been enough to restore the kākāpō to healthy numbers, partly because of their distinctive breeding system. Kākāpō on these islands only breed in years where the rimu tree masts (fruits heavily), which can be up to five years apart. Dr Andrew Digby of the New Zealand Department of Conservation told IFLScience that in parts of New Zealand where the kākāpō are now extinct, they probably once timed their breeding to other trees, which fruit more frequently, but still not every year.

“One kākāpō female first nested in 1981, and then the next time was 2006,” Digby told IFLScience. She’s still around today, and the team is hoping for a hatchling from her soon, but it’s not exactly a breeding cycle suited to rapid recovery, particularly since clutches are of only 1-3 eggs.

As if that wasn’t bad enough, only around 40 percent of eggs hatch, with many being infertile from the start. Digby attributes this in large part to inbreeding following the isolation of kākāpō populations after human arrival. Other problems include cold snaps killing the eggs if the mother doesn’t incubate well enough and, on one island, battles over nesting sites between kākāpō and petrels. kākāpōs usually win these battles, often ruthlessly killing the petrels, but the egg can get crushed in the fight.

A Little Help

Another species with so much against it might be left to its own devices, but New Zealanders love their birds, and the kākāpō is a particularly charismatic creature, whose eccentricities only enhance its popularity. 

We’ve also tried remote control cars dressed as a female, but neither worked too well.

Dr Andrew Digby

Consequently, when the rimu masts, great efforts are made, which in 2009 included probably the first artificial insemination of a wild bird. That effort was not particularly successful, but the team involved has kept trying and now reports that things went a lot better in 2019.

Kākāpō females frequently mate with several males before laying eggs, allowing sperm competition to decide who will father their young. Females who do this have far higher breeding success than those that, for whatever reason, only mate with one male a season. However, with small populations, multiple mating doesn’t always occur.

Digby and colleagues decided to replicate this natural behavior. Every kākāpō carries a tracker, allowing the team to know when the females have visited the bachelor pads males construct in mating seasons. Once a female had mated once, the team would determine if they considered her choice a “suitable match” in Digby’s words. It may sound like something out of Bridgerton, but with so much inbreeding, the team would rather avoid too much mating with close relatives.

When the team decided the female could do better, they artificially inseminated her, often with the semen of several unrelated males. The team was particularly keen to spread the precious Fjordland genes.

Fiordland was the last area of New Zealand’s main islands where the kākāpō survived. Seeing no future for them there, biologists moved the few survivors to the protected islands. Unfortunately, all those transported have since died, with only one, Richard Henry, fathering offspring. Richard Henry’s children could be the key to building genetic diversity, so the team made extra efforts to collect semen from his offspring.

How To Get Kākāpō Semen

Artificial insemination requires semen collection, and with kākāpō, that’s not easy. Famously, biologists have previously worn hats they hoped would arouse the passions of male kākāpō with brims that would funnel semen into tubes. “We’ve also tried remote control cars dressed as a female,” Digby told IFLScience, “but neither worked too well.” 

A human can outrun a kākāpō over open ground, but they can run through thick forest faster than us, and can climb trees better than us. Sometimes we go to catch the female, and she is up a tree or in a burrow and [the semen’s] wasted.

Dr AndreW Rigby

Instead, the authors called in help from bird inseminators worldwide, which in 2019 included Professor Michael Liez and colleagues at Justus Liebig University Giessen. Using their advice, the team tried capturing the males and performing abdominal massages on them, or electrically stimulating the cloaca, both of which are described in great detail in their paper on the efforts.

“Both worked, but we didn’t pursue the electrical stimulation because it was more invasive and didn’t work as well as the massage,” Digby said. And for that, the kākāpōs were no doubt very grateful. You’ll be pleased to know the males were given the appropriate food reward of a nut to thank them for their contribution.

The process is particularly challenging because, Digby explained, kākāpō semen works best fresh, and quality “declines by the hour”. Semen supplies have even been sent by “spermacopter” drone across the island to minimize delays. Several samples were often combined to maximize the chances that one would be healthy enough to fertilize the female, but she still needs to be caught.

“A human can outrun a kākāpō over open ground,” Digby explained. “But they can run through thick forest faster than us, and can climb trees better than us. Sometimes we go to catch the female, and she is up a tree or in a burrow and [the semen’s] wasted.” Who can blame her after all, with these meddlesome humans attempting to interfere with her preferred romance?

Once caught, the paper says the female kākāpōs were held recumbent “And their feet slightly pulled to both sides. Meanwhile, their head and wings were gently constrained using a towel to prevent wing flapping or other movements.” Where appropriate, their cloacae were cleaned before a speculum and catheter were inserted. “After the procedure… the tail was gently articulated to simulate natural tail movements after copulation before they got rewarded and were released.”

Digby, who did a PhD in astronomy before a second on kiwi conservation, politely avoided IFLScience’s question of whether massaging kākāpōs to happy endings and extracting sharp-beaked avian Juliettes from burrows ever made him reconsider his life choices.

Given the loss rate even of fertile eggs, the team often take the eggs to incubate them, leaving the females with replicas, before returning them prior to hatching to be raised by their own kind. (Male kākāpō are no help here).

By the numbers

All these efforts are not in vain. By 2019, numbers had rebounded to 142. That year’s breeding program inseminated 12 females and resulting in 14 fertile eggs out of 20 laid (70 percent). In contrast, only 29 percent of the eggs where artificial insemination was not performed were fertile. 

Moreover, the efforts led to Sinbad, son of Richard Henry, fathering offspring for the first time, passing on those precious Fjordland genes.

The team hopes to get the population to the point where less intervention is required, and the birds can be left more to their own devices, particularly in regard to incubating their own eggs.

Digby thinks lessons learned in the program will be applied next mating season, expected next year, and could also prove useful for some other endangered birds, even if no one mates quite like a kākāpō.

The study is published open access in PLOS ONE.