AROUND THE breakfast table in our hut on Codfish Island, or Whenua Hou, the conversation invariably turns to sex. In particular, the nocturnal comings and goings of the residents of this remote isle: their courtships, couplings, triumphs, disappointments and strange proclivities animate our early-morning gatherings, and there isn’t much that escapes attention. A high-tech surveillance network ensures that trysts between locals such as Sue, Lisa, Flossie, Jimmy, Ben and Lionel rarely go undetected. In fact, they are diarised, cross-referenced and discussed in depth.
Such seemingly prurient interests start to make more sense when you understand that the resulting offspring of these alliances will be among the rarest and most-valuable new arrivals on the planet. For these island dwellers are kakapo, a species of bird teetering on extinction, and the observers are the Kakapo Recovery Team, the members of which are hell-bent on slowing this strange green parrot’s slide into oblivion.
A 1396ha speck off the southern tip of New Zealand’s South Island, Codfish lies to the west of much larger Stewart Island. Islands and their unique geographic features have been inexorably linked to the evolution and fate of many endemic New Zealand birds. With no ground-living mammalian predators to threaten them, numerous flightless species developed here (see page 62). Among them are 11 species of giant moa, all now extinct, and the kakapo.
Today, Codfish Island provides hope and safe haven for the kakapo. It also acts as a hilly, windswept laboratory for the scientists, technicians, rangers and volunteers who discreetly manage every aspect of the lives of these otherwise wild birds.
The kakapo is a very peculiar member of the parrot family, not least because it is the only one that has lost the ability to fly. Its scientific name, Strigops habroptila, describes its owl-like face and the softness of its feathers, while its common name, kakapo, means ‘night parrot’ in Māori. As that would suggest, it’s a nocturnal creature that hides under logs and grassy tussocks during the day, emerging after dark to forage and mate.
So much about this bird remains shrouded in mystery, but its natural history is slowly being unravelled through prolonged close observation, meticulous record keeping and DNA analysis. We now know kakapo are very long-lived and some may reach 90 years of age or more.
Most parrots form monogamous pairs that bind them for life, but not the kakapo – it’s a ‘lek breeder’, whose males perform elaborate courtship rituals to attract females to their ‘leks’ or territories. Females usually mate with several partners. In an evolutionary strategy almost guaranteed to result in failure, reproduction is inextricably and curiously linked to the irregular and infrequent fruiting of a singletree, the rimu.
I’VE JOINED THE Kakapo Recovery Team on Codfish Island for the February 2013 breeding season. It is forecast to be a dud year as the rimu’s fruit crop is poor (kakapo eat a range of plants, but rimu fruit is their super food, packed with the nutrients brooding females require as they raise their young alone).
Undeterred by poor prospects, Deidre Vercoe, Kakapo Recovery Programme manager, says the team are taking the opportunity to hone their methods for extracting and preserving kakapo semen. The sperm collectors, nicknamed the ‘Love Team’, are here every year at this time.
If any natural matings are suspected, the females in question receive a top-up, technical officer Daryl Eason tells me. “Some of the birds will mate twice – sometimes with the same male or two different males. The birds that mate twice have a much higher fertility rate. We can’t make them all mate several times, so the way we do it is by using artificial insemination,” he says.
The donor males are specially selected to optimise genetic diversity, Daryl says. “It’s a double-edged approach to improve fertility...and ensure that some of the founders get an even spread of matings.” Among these founders are Sinbad and Gulliver. Every living kakapo is rare and precious, and each has a name, but these two birds, and their sister Kuia, are particularly significant: they are the only living progeny of the last surviving mainland population.
Kakapo were once abundant on the terrestrial predator-free idyll that was New Zealand before human settlement. But things changed rapidly when Polynesian colonists arrived 700–900 years ago, bringing hunting dogs and inadvertently introducing stowaway Polynesian rats, or kiore. Things took an even worse turn with the arrival of Europeans in 1769. They brought a great wave of creatures (two varieties of rat, followed by cats, rabbits, stoats and weasels) that would sound the death knell for many natives.
Flightless, fearless, defenceless and with an attractive scent, kakapo were ill-equipped to deal with such a deadly cocktail of predation, which was exacerbated by habitat loss (see Dead as a dodo, AG 114). By the early 20th century, the only kakapo that remained were found in a number of populations living high on the wild, steep slopes of the Fiordland region, deep in the South Island’s south-west.
A rescue plan by far-sighted early conservationist Richard Henry saw the world’s first attempt to establish an island sanctuary for a threatened species. In the 1890s Henry shipped more than 700 kakapo and kiwi to Resolution Island, between Dusky and Breaksea sounds. But by the 1940s, all the birds were gone, wiped out by wily stoats, weasels and ferrets, which simply swam there.
Other populations suffered similar fates, until only one wild group was thought to remain, and from the 1950s to the 1970s, kakapo were more or less considered doomed. That was until a sizeable, mixed-gender population was discovered on Stewart Island in January 1977. It was moved to predator-free Codfish Island in the ’80s to safeguard it from cats. Another 18 males were captured in Fiordland between 1974 and 1978, and some of these were also eventually moved to Codfish, thereby launching one of the most ambitious species rescue efforts ever attempted.
I’M KEENLY AWARE of how privileged I am to be here on Codfish. Access is, justifiably, strictly controlled, and the rigorous quarantine check prior to boarding the chopper flight here drove home just how hard-won its predator-free status is. Once the formalities are over, I’m warmly welcomed into the fold and the humble knot of timber huts that make up Kakapo HQ. It’s no luxury “Resort and Spa”, as the humorous sign on the door suggests, but it’s warm, the food is good and plentiful, and the chat around the enormous table is lively.
Previous guests here have included British author Douglas Adams and comedian Stephen Fry, both of whom came with zoologist Mark Carwardine. Mark’s painful amorous entanglement with Sirocco the kakapo (who attempted to mate with his head) was broadcast in the series Last Chance to See, and became an online sensation. This interest put the conservation effort on the map and made a celebrity of Sirocco, who now has his own Facebook page and Twitter account, and who acts as a charismatic conservation ambassador for the kakapo.
On my first day in the field I join the Love Team as they effortlessly shin up steep, muddy tracks towards the top of the island. I’m with Deidre, Daryl and Jo Ledington from the Kakapo Recovery Programme, as well as cryobiologist Samantha Gale and technician Ellie Watts from the Nelson-based Cawthron Institute.
I struggle to keep pace, but we mercifully come to a halt in a clearing and, by the time I catch my breath, they’ve broken out their bush laboratory and are ready to hunt kakapo. They pick up the signal of a tracker and dive into dense bush. Within minutes, Jo spots her quarry as he climbs into the canopy of a tree. She follows him up and carefully snatches him off a bough, then places him in a hessian bag and we return to the clearing.
He’s identifed as Blades, a big male, and, as they examine him, I’m invited to feel the dual air sacs either side of the parrot’s chest. Blades looks me in the eye and holds my gaze rather defiantly – or so it seems to me – so I silently apologise for the intrusion. The two sacs are huge beneath the soft feathers. They need to be, for they produce the boom that’s the most distinctive feature of the kakapo’s unique mating ritual.
During the breeding season, males move to higher ground, where the vegetation is less dense, and excavate a series of shallow bowls linked by tracks, which forms their lek. At night, they stand in their bowls and boom. This deep, resonant call – interspersed with a high-pitched “ching-ching” sound – is amplified by the air sacs and can be heard up to 5km away.
Although effective at attracting willing females, this elaborate display can’t be solely relied upon to guarantee reproduction. DNA sequencing is used by the researchers to work out who is related to whom, and also to discover the best matches to avoid the problem of inbreeding. The team can then focus their artificial insemination (AI) efforts most effectively.
Daryl explains that there’s a particular problem with inbreeding in the birds from
Stewart Island, which has reduced their fertility rates. “A lot of the males have deformed sperm, especially the sperm heads, and, in combination with inbred females, this leads to early embryo death. About 40 per cent of the eggs will be infertile, and an additional 20 per cent will die, usually in the first 10 days,” Daryl says.
If the chicks get to the hatching stage, survival rates are high because of the intensive care they receive. That’s why increasing fertility is the activity on which the team focuses. “Because it takes 9–10 days from mating to laying, that gives us a great window,” Daryl says. “So, if we keep a close eye on which female birds are mating, who they mated with, if they made a good genetic choice, and if they mated twice or not, then we can decide whether it’s worthwhile to follow up with AI.” If a female hasn’t followed up an initial mating within five days, the scientists usually collect sperm from 1–3 males with which to inseminate her.
Daryl and his co-workers make catching kakapo and extracting sperm look almost easy, but there’s no doubt they are well practised at this difficult task. Today we are collecting sperm to trial preservation methods, with the goal of successfully freezing it without reducing its viability. Just two kakapo have resulted from AI so far; both from freshly harvested sperm in 2009, the last big breeding year.
The Stewart Island founders are now dying off and their DNA desperately needs to be preserved – it has more genetic variation than that of the newer generation reared by the rescue program (the last Fiordland bird, named Richard Henry, died in 2010 but not before passing on his genes to Sinbad, Gulliver and Kuia).
WE REPEAT THE handling procedure numerous times over the next few days, as Deidre, Daryl and Jo perform a series of health and equipment checks. Most kakapo succumb quietly to the disturbance. Others protest with loud “skraaarks” or throaty growls.
Each bird wears a small transmitter on its back, and Jo tells me that technology is integral to the rescue effort, opening a much-needed window onto the kakapos’ secret world. “We couldn’t manage them to the extent we do without the transmitters,” she says. “They tell us so much about their behaviour.”
The devices relay signals back to base camp, alerting rangers to a range of activities, including visits to feeding stations, mating, nesting and, occasionally, deaths. The Kakapo Recovery Programme is labour intensive and costly, but clever technology is scaling back human intervention, while allowing the birds to live in a genuinely wild state.
Deidre is positive about the future. “The population has more than doubled since the program began in 1995 with 51 birds. There are now 124 and the age structure is a lot better. At the start it was 95 per cent old birds,” she says. “Now it’s almost reversed…we’ve been able to rebalance it so that the population is mainly made up of young, breeding-age birds and…we’ve balanced out the sexes again, so that there’s almost a 50–50 split.”
Giving the birds supplementary food increases the number of eggs laid, and years of trial and error have led to the development of a potential rimu substitute
that could eventually allow mothers to raise chicks if the fruit crop fails. The experts also realised there was a link between the weight of a mother and the sex of her chicks, and have used that information to redress the vital gender balance.
There are now managed populations on three other islands, Anchor, Maud and Little Barrier (Hauturu). The populations on each have been separated from one another to maximise genetic diversity and it’s hoped that more islands can be prepared as the population continues to grow.
There can be very few species that are managed as intensively as the kakapo. And, in the face of great conservation problems across the world, it might seem a luxury to devote so many resources to a single species that, in the long-term, may already be genetically doomed because of its population bottleneck.
But to New Zealanders, the species is iconic, and the things that made it vulnerable in the first place – its inability to defend itself, its flightlessness and trusting nature – are all factors that have made it much easier to care for and study. The trailblazing conservation efforts for the birds are also providing invaluable information and techniques that can be applied to a whole spectrum of species under pressure.