Extensive trapping boosts number of critically endangered kakī

Friday, 22 May 2020

Kakī being released into the wild near Mt Gerald Station in August 2019.

Extensive trapping has given a big boost to a critically endangered Canterbury wading bird that once had a population of just two dozen.

A population survey this year found 169 known kakī/black stilt living in the wild in the Mackenzie Basin, between Tekapo and Twizel.

It is equivalent to the population increasing by almost one third again. The 2019 population was estimated at 132 adults.

Kakī numbers are benefiting from an extensive trapping programme in the Mackenzie Basin.

The success is down to a multimillion-dollar trapping effort by conservation group Te Manahuna Aoraki that expanded last year. More than 2100 traps were set across 60,000 hectares of habitat — about 80 per cent of the area in which kakī live.

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Kakī juveniles are a mixture of black and white until their fully-black adult plumage comes in at about 18 months.

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The world's rarest wading bird, kakī live in braided rivers and swamps and are highly susceptible to predators, especially ferrets, feral cats and other mammalian predators.

The Department of Conservation (DOC) released 184 juveniles after a particularly successful 2017-18 breeding season, but only 67 survived.

Another 134 juveniles were released in August 2019. They are not yet included in the population count as they have not reached breeding age.

Conservation Minister Eugenie Sage said the population increase was the largest seen in the almost 40 years the kakī conservation programme has been running.

“Today’s (Saturday's) announcement is a tribute to nearly four decades of protection, research, and intensive management.

'Kakī have had a remarkable turnaround since they were on the brink of extinction in 1981, when the adult population declined to a low of just 23 birds.'

The population survey was done during the recent breeding season, with DOC rangers able to analyse the data from home during the Covid-19 restrictions.

There are 116 juveniles and 11 adult kakī in captivity in aviaries in Twizel and at the Isaac Wildlife and Conservation Trust in Christchurch.

Staff cared for the birds throughout the restrictions, following strict hygiene protocols to protect the health of both the birds and staff.

The young kakī will be released into the bed of the Godley River, near Aoraki/Mt Cook, in August.

This season, eggs were collected from three captive pairs and 26 wild breeding pairs and artificially incubated.

The young chicks are raised in captivity, held over winter and released into the wild when 9 months old.

Kakī are a taonga species for Ngāi Tahu.

Conservation efforts suffered a setback after the roof of an aviary in Twizel collapsed under heavy snow in 2015.

A new $500,000 aviary was built in 2017 after funding was provided from an American conservation organisation.

Kakī are unusual in that they stay in their riverbed habitat all year around, despite the water sometimes freezing over. Most river birds move to the coast during winter.

They often pair up for life, but if they cannot find another kakī they may breed with pied stilt/poaka — though occurrences of this have reduced through intensive management.

Kakī juveniles are a mixture of black and white until their fully-black adult plumage comes in when they are about 18 months old.