Kākā take on exotic trees, and win
Kākā are fighting back against introduced trees in Wellington.
Their latest victims are two giant redwoods in Wellington Botanic Gardens that have been stripped of their bark by kākā, which enjoy feasting on sap.
Tim Park, manager at Ōtari-Wilton’s Bush, said kākā were the ultimate success story for the predator-free movement in Wellington.
Kākā were extinct in Wellington until a small number were released in Zealandia in 2002.
Now a regular sight in the skies above Wellington, they have one habit that not everyone is happy about.
“They habitually remove bark from trees and lick the sap, they have a little brush-like tongue,” Park says.
They were once widespread in Wellington, and European settlers dined out on kākā meat. It was sold in shops alongside poultry ,and Park had a reference from 1870 recording someone having a wheelbarrow full of kākā destined for the table.
It was, however, possums that wiped out the noisy parrot, which can now be seen in big numbers in suburbs such as Kelburn, Ngaio, Karori and Mt Victoria.
Ōtari-Wilton’s Bush has played a key role in their return to Wellington.
Kākā like to breed in natural nesting holes found in natives such as tawa and hīnau, two species common in the reserve.
Native trees have evolved with kākā and have a natural defence, which means they can survive having bark removed.
Kākā can now be seen in big numbers in Ōtari-Wilton, where they nest and flock to at night. “I see flocks of up to 30 on a good day and I see at least a dozen flocks.”
Before the pest-free movement removed possums from the region, kākā were vulnerable to the Australian pest, which feasted out on their eggs and chicks.
Scientist Nikki McArthur has been doing a bird count across the region for more than a decade and has witnessed the return of a number of native species, including kākā, kererū and tūī.
Ōtari-Wilton was a “hot spot” for the increase, with kererū doing particularly well, he said.
“The steepest increase in any species has been kererū, which had tripled in number across Wellington, and they are going absolutely gang busters in Ōtari.”
The increase in kākā and their impact on trees, has not been without controversy. As well as stripping trees, kākā are noisy but Park is unconcerned about the damage done to exotic trees, noting kākā are a taonga species.
“When I was a kid, I would never have imagined kākā as part of my life.”
Across the region, the damage done by kākā was insignificant when compared to the pleasure they gave Wellingtonians, he said.
The success of kākā at Ōtari-Wilton showed the importance of the reserve and the need to protect the natural environment. Ōtari-Wilton’s Bush is rated as a six-star Garden of International Significance by the New Zealand Gardens Trust of the Royal New Zealand Institute of Horticulture.
It has the single largest collection of New Zealand native species, and its podocarp/ northern rātā forest is one of the few remnants of the forest that once covered the Wellington Peninsula.
The Ōtari-Wilton’s Bush Trust recently launched an endowment fund, with support from the Nikau Foundation, to support native plant conservation at the reserve.
The trust has 100 volunteers who support the reserve by doing everything from weeding to pest control, and acting as guides for visitors from cruise ships.
The reserve has 1200 native plant species, and Park said it was also doing valuable work storing seeds and researching native fungi.
It was extra special to see kākā doing well in the reserve, as its original name was Ōtarikākā, meaning the place to snare kākā, he said.
One of the seed species it is saving is kakabeak, a stunning native with a distinct red flower, which is almost extinct in the wild.