The Secrets of Kakapo

 

Being a New Zealander keen on understanding conservation can be challenging. Due to the unique state of our wildlife, most articles and information are tailored for those just beginning to explore our distinctive species. While this approach serves a purpose, providing basic information for those discovering the Kākāpō for the first time, it can be limiting for locals who wish to delve deeper into the world of Kākāpō.

My intention is to take the opposite approach. I aim to offer well-written, in-depth articles that both entry-level readers and those familiar with New Zealand Conservation can enjoy. With that in mind, here are three Kākāpō facts that even a super fan might not know!

Rangi the Master of Kakapo Hide and Seek

Rangi is often credited as the reigning Kākāpō hide-and-seek champion. In 1987, Rangi was released alongside three other male Kākāpō on Whenua Hou, off the Southland Coast. All four males had recently been discovered living on Stewart Island, and they were translocated to shift them away from feral cats, which had decimated the Kākāpō population.

Back in the 1980s, Kākāpō transmitters cost exorbitant sums of money, and the decision was made to minimize costs and release the males without transmitters. Whenua Hou is a small island, and it was reasoned that it wouldn't be too hard to relocate the Kākāpō again. All four would be turned loose over several months, and none would ever be seen again. For twenty-one years, they were believed to be dead or lost forever.

In the summer of 2009, a ranger was working in a remote area of the Whenua Hou coastline when he was surprised to hear booming. Few male Kākāpō inhabited the area, so he quickly moved in to investigate. Amazingly, he discovered Rangi, who was in both good health and unperturbed at having been missing for so long.

News travelled quickly, shocking many worldwide. Hundreds of scientists and thousands of volunteers have visited Whenua Hou over the years. How could a bird escape detection for two decades on one of the most intensively studied islands in the world?

It's helpful to remember that Kākāpō are nearly invisible in the forest. They've evolved to evade detection from predators by blending into the background of the canopy. Prior to the introduction of pests to New Zealand, Kākāpō faced predation mainly from raptors such as the Eyles Harrier and Haast Eagle. Freezing allowed them to avoid detection from the air.

Such was the effectiveness of this camouflage that hand-reared Kākāpō Hoki would evade detection for hours in her aviary. At one stage, she blended so well into the bushes in her enclosure that she was declared to have escaped. Only when she blinked did she reveal herself.

Kakapo can remain hidden for decades

The 'Lost' Kākāpō 

Kakapo Mike has been 'missing' for forty years.

Kākāpō and Troubling Genetics

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According to the Kākāpō Recovery Team, between 1974 and 1997, 65 Kākāpō were translocated from Stewart Island and Fiordland to offshore islands. Today, the Kākāpō population stands at approximately 250 birds. However, these numbers may mask something a little more sinister: how badly Kākāpō are affected by inbreeding depression.

Exact estimates vary, but it's generally believed that it takes approximately fifty unrelated individuals in a population for a species to survive the negative impacts of a genetic bottleneck. Much beyond that point, there is serious concern that the species may see a genetic collapse, and a high risk of eventual extinction.

Theoretically, Kākāpō should have just enough unrelated individuals to avoid such complications. Sadly, upon closer examination, this is not the case.

Firstly, it's helpful to understand where that figure comes from. It's the cumulative total of birds who were translocated from Fiordland and Stewart Island and survived until release. Unfortunately, it's a rather arbitrary figure, primarily because we're examining data across a 23-year period. Certain Kākāpō were born, lived, and died during that period, all without being included in that figure. Other Kākāpō who died prior to them are counted.

Things become even more muddled when you consider that we count birds who died immediately after translocation, but not those who died during the process. I think a better way of understanding the genetic bottleneck Kākāpō have gone through is to examine how many birds actually survived to pass on their genes.

It's not fair to compare Kākāpō populations either. Intensive search efforts between 1974 and 1981 would reveal a population of 100 to 200 Kākāpō on Stewart Island, and eighteen birds in Fiordland. Though only 95 Kākāpō were ever actually found during intensive searches of Stewart Island, and from that number, an estimate of 100 to 200 individuals was extrapolated.

In Fiordland, eighteen birds were found, the majority of whom were found in Milford Sound. However, only twenty percent of the Milford area was searched, and no population estimate was made. Examination of the Kākāpō search notes indicates the presence of birds that were never captured. In fact, if we were to take the total Kākāpō sign seen and multiply it by the size of the catchment region, it's not unreasonable to believe the two populations were of comparable size. Though the Fiordland birds were likely located in a much more inaccessible area.

Not all Kakapo survived their transfers

Kākāpō & the impact of Inbreeding.

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Of the 113 Kākāpō actually found across both locations, forty-nine would die or disappear prior to translocation. In the majority of instances, these birds would have been killed by introduced predators, either cats or stoats. The Kākāpō recovery team would attempt to translocate the remaining sixty-nine individuals, though mortality would be high, particularly amongst birds of advanced age. Only fifty-three Kākāpō would survive more than two years on offshore islands, including just one Fiordland Bird, Richard Henry.

Unfortunately, the bottleneck would only be exacerbated from there. Since the first successful offshore breeding season in 1991, only thirty-nine of these birds would go on to produce living offspring. Nor does that paint a full picture. In 2002, the development of genetic testing allowed researchers for the first time to examine Kākāpō micro-satellite DNA paternity markers. The results were grim: Merty, Sarah, Wendy, Zephyr, and Heather were, in fact, second-generation chicks, who had both parents still living.

In 2009, the technology was advanced several steps further, allowing researchers to begin confidently assigning family relationships between birds. Many birds share enough markers to suggest either a sibling relationship or that they are first-order relatives. We now believe that Lisa and Ralph are probably siblings, which isn't ideal because they're both also the parents to Merty. Moreover, two prolific females, Margaret Marie and Suzanne, appear to be sisters.

That isn't the end of things either. Four pairs of birds appear to be closely related, though how isn't clear. These include Arab & Sass, Smoko & Whiskas, Barnard & Jean, and Ox & Waynebo. These birds may share a parent, grandparent, or be the grandparent of the other.

In addition to these birds, two founders, John Girl and Pegasus, died after producing a single chick together in 1991, effectively merging their genetic potential into a single lineage through their chick Stumpy. All up, there seems to exist about twenty-nine distinct Kākāpō lineages, only half the number needed to guarantee a species will survive a bottleneck.

This doesn't necessarily mean Kākāpō will become extinct, however, it does indicate that there will be some unique challenges the species will face when it comes to fitness, fertility, and the risk of disease. These factors will leave them vulnerable to new threats.

Thankfully, some recent evidence suggests this isn't the first bottleneck Kākāpō have survived, and they may have evolved to be better suited to surviving bottlenecks than other parrots.

But that's something we will save for another story.

Only a handful of Kakapo contributed to the modern population

Exploring the Link Between Kakapo and Kokako Sightings

Perphaps one of the most facinting aspects of the story of the Kākāpō comes from the link between it and another 'recently extinct' bird the South Island Kōkako.

The South Island Kokako and Kakapo appear to have inhabited the same areas. In November 2021, hikers near the Percy Burn Viaduct in Southern Fiordland reported hearing potential Kokako calls. The Percy Burn Viaduct leads into a set of hills containing the Wairaurahiri River headwaters, commonly known as the Angus Burn. In 1992, these headwaters were the focus of a major search for Kakapo after hikers reported booming from the slopes of these hills.

In January 2022, audio records of Kokako calls were submitted to the Department of Conservation from the Heaphy track, where Kakapo were reported booming until 1981, and possible track and bowl systems were found as late as 1984. In 1998, Dan McKinnon reported seeing a Kokako east of Punakaiki. This is notable because a Kakapo nest was found here by prospector C.W Wilks in 1948, marking the last recorded nest on Mainland New Zealand. Additionally, Kakapo were seen here by Wilks and other prospectors in 1955, 1958, 1959, and 1964.

The similarities do not end here. A potential Kokako sighting was logged in 2021 from the Coupland Valley track, less than a kilometer from a set of bluffs where a Kakapo was observed in 1985. In 2007, a Kokako was heard calling in Ships Creek South Westland, just two kilometers from where a Kakapo was observed running across a road in 1984. In 2011, a Kokako sighting was observed from the Paringa River, near where a Kakapo was observed by two brothers tramping some decades earlier.

South Island Kokako seem linked to the Kakapo

Kakapo and Kokako: A Linked Legacy

In 2000, a Kōkako was heard calling in the Tutuko Valley, several kilometres from where Kākāpō were last recorded in 1988. In 2006, possible South Island Kōkako feathers were found in Crayfish Heights, just below a ridge where Dick Decker observed an active Kākāpō track and bowl system in 1985.

Many of the most recent Kōkako sightings have come from Fiordland. In 1987, a Kōkako was sighted on the Carrick River, where a Kākāpō had been observed booming in both 1983 and again in 1985. Moreover, active track and bowl systems were found in the nearby Oho Creek at the same time. A Kōkako was heard by Mo Turnbull in Big River in 2004, and the same year, a Kākāpō was reported by Wayne Durant in the headwaters of the same river in the Jeanie Burn.

Even on Stewart Island, Kākāpō and Kōkako reports came from the same locations. A team searching for Kākāpō in 1985 made note of three instances of hearing or seeing Kōkako. An additional three more reports would come from the same area in 1986 and 1990, near the Southern end of Mason Bay. In 1997, a hunter observed a Kākāpō in the same area.

All this serves to reinforce the validity of these claims. It seems extremely unlikely that two critically endangered birds would have such an overlapping distribution of claimed sightings unless there was some truth to them. We explore more about the South Island Kōkako and it's story here

Many sightings of Kōkako and Kākāpō are from the same locations 

Enjoy this style of investigative journalism? Why not read our article of how political infighting nearly lost us the Kākāpō forever? 

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Thanks to Dr Andrew Digby for the use of his photos