Keeping the kokako’s song alive

Kokako had the researchers stumped for a while. Kokako couples observed in the wild seemed to be doing all the right things: defending their territories, showing courtship behaviour, forming pair bonds, building and occupying nests – and yet few kokako chicks arrived.

Finally they twigged: many of the kokako couples were male-male pairs. Naturally these civil unions weren’t going to produce any offspring.

Male and female kokako are so alike that you have to DNA test them to determine which is which. And kokako are highly unusual among birds in forming male-male pairs. They are also long-lived – about 20 years – so you would still see kokako around for years even if they weren’t producing any young.

So it took a while for those trying to help restore kokako numbers that many wild populations comprised mostly – if not totally – male kokako. The females, which are highly vulnerable to predation while nesting, had been all but wiped out by introduced pests.

The remaining male-dominated populations, not replacing themselves with offspring, were gradually dwindling away to nothing.

These days, this mystery and many others surrounding this fascinating forest bird have been cleared up due to years of dedicated research, and those working to boost kokako numbers have a pretty good idea of what the problem facing kokako is: predation of chicks, eggs and even adult birds on the nest by rats and possums.

They also know what the solution is: intensive pest control, particularly around the breeding season. Keep possum and rat numbers low in key sites and kokako numbers will grow.

And grow they have. The Kokako Recovery Group’s 20-year goal, set in its 1999 Kokako Recovery Plan, was to restore numbers to 1000 pairs by 2020.

At the time the plan was drawn up there were about 350 pairs left, most in small, isolated populations confined to the upper half of the North Island.

Now, according to Ian Flux of the recovery group, they are well ahead of meeting their recovery target. There are currently 750 pairs of kokako and the group expects to meet the goal of 1000 pairs by 2013 – seven years earlier than expected. And, yes, those pairs are genuine male-female pairs – the population has a fairly even male/female split now.

The recovery group is now considering an update to its plan setting a higher target number of kokako, and probably increasing the number of sites where kokako are protected from predators.

Flux says the goal has been achieved (or over-achieved) by a strategy of focusing on key sites where kokako populations can be protected by intensive pest control.

The kokako had been an icon of campaigns by conservationists (including Forest & Bird) in the 1970s and 80s to stop logging of native forests. But even once the kokako habitat in those forests was protected from the logging threat, kokako populations were still plummeting as introduced pests continued to take their toll. Without help it faced almost certain extinction.

The recovery group established 24 key sites around the North Island where intense management would allow kokako populations to recover, safe from the ravages of pests.

“There were kokako in ones or twos scattered all over the place but if we chased them all we’d get nowhere, so we had to focus our efforts. Initially the total population went downhill, but it quickly swung around as the populations in the managed sites recovered,” Flux says.

The recovery group also decided to concentrate its efforts mainly on mainland sites, rather than move all the birds to offshore islands. It was decided that while the birds could be protected more easily on island havens, it was important to maintain kokako populations on the mainland, where people could more readily see and hear them.

A few of the key sites are protected by predator-proof fences, but most are “open sanctuaries” where pest numbers are kept low by use of poison baits. The recovery plan probably would not have succeeded without the poison 1080, Flux says.

“It has been absolutely essential – we would have lost a lot of the kokako populations if it wasn’t for 1080. It has been key to restoring this species.”

The results at individual sites have been dramatic. At Mapara in the central North Island there were just three breeding pairs of kokako left. Following three aerial applications of 1080 followed by its use in bait stations, there are now 75 pairs there.

As well as protecting the birds from the key threat of predators, the recovery group has also undertaken genetic research and have transferred kokako between different sites to ensure that their populations have a diverse genetic base.

Flux says pest control aimed at protecting kokako has also had benefits for other forest species, with other birds including kiwi, whitehead, kereru, shining cuckoo and kaka, as well as threatened native plants such as kaka beak and Dactylanthus thriving in the pest-managed sites.

Flux says that while the kokako’s future is looking much brighter thanks to the work that has been done, it is not out of the woods yet.

He would like to see large kokako populations established in more pest-protected sites throughout its former range.

There are plans to reintroduce kokako in areas such as the Waitakere Ranges, Hunua Ranges and Maungatautari Mainland Island – places where people will be able to hear the kokako’s haunting song and appreciate what a treasure we have, and nearly lost.

North Island Kokako (Callaeas cinerea wilsoni)

The kokako belongs to the ancient family of wattlebirds, which also includes the saddleback and the extinct huia.

It is a fairly large bird, weighing about 230 grams, with powerful legs that it uses to leap about the canopy. The kokako has blue-grey plumage and a black “Lone Ranger” mask and bright blue wattles.

It was called the blue-wattled crow by early European settlers but is not actually a member of the crow family. Kokako are believed to live for 20 years or more.

Kokako eat a variety of food, including fern fronds, leaves, flowers, nectar and fruit of native plants, as well as insects.

The kokako is renowned for its loud and haunting song, most often heard at dawn, and each population has its own distinct “dialect.”

Kokako defend large forest territories (from 4-20 hectares) and form pair bonds which can last for years.

The breeding season is mainly from October to March, when females do most of the construction of nests built from twigs and other plant material, and lay 1-3 pinkish-grey eggs, which take 18 days to hatch. The chicks then take another 30-35 days to fledge.

Ian Flux of the Kokako Recovery Group says the movement of the kokako in the canopy is as much like a squirrel as a bird, bouncing from tree to tree using its powerful legs and using its wings in short downward glides, rather than sustained flight.

Legend has it that the kokako assisted Maui as he battled the sun by carrying drinking water to him in its wattles. Maui is said to have rewarded the kokako by giving the bird its long, strong legs.

Kokako were once widespread throughout forested areas of the North Island, but habitat destruction and predation by rats and possums wiped out most of them.

The South Island kokako (C. c. cinerea) is believed to be extinct. Flux says he doesn’t share the hopes of those who believe the South Island kokako is still alive in Fiordland – he says the kokako’s song and appearance is so conspicuous that if they were present, they would have been found.

It is widely thought that North Island kokako had blue wattles and their South Island cousins had orange wattles, but the split may not be so clear-cut. Flux says orange-wattled kokako have been observed in the North Island as recently as a few years ago. The base of the South Island kokako’s wattles were blue, with orange only at the ends, but collectors in past centuries often painted the wattles of their museum specimens a brighter orange all over.

The Kokako Recovery Group

The Kokako Recovery Group comprises Department of Conservation staff and other scientists and conservationists (including Forest & Bird) who undertake research, pest control, translocations and other work to ensure the species can recover. The group works closely with communities and tangata whenua to involve them in the kokako’s recovery. The group’s 1999-2009 Kokako Recovery Plan sets long-term goals and strategies for the recovery of the species.

Our Appeal

Forest & Bird’s annual Dawn Chorus Appeal aims to help protect kokako and other native dawn chorus birds from the threat of introduced pests.
Look out for the appeal envelope in your letterbox in November or you can donate online at www.forestandbird.org.nz. Your support can help keep the kokako’s song alive.

Keeping the kokako's song alive (PDF)