No kōkako chicks survived in four monitored nests this summer at Forest & Bird’s Ark in the Park in the Waitakere Ranges.
High numbers of rats and other predators appear to have destroyed all the chicks and eggs in the kōkako nests under volunteer surveillance in the reserve, says Waitakere Forest & Bird branch chairperson Annalily van den Broeke.
“The loss of every single egg and chick we saw this breeding season is terribly sad for the kōkako," says Mrs van den Broeke.
"In the Ark, there are only about 60 kōkako and nationally about 3600 remain, so this is pretty heartbreaking.”
Between February and August 2019, rat numbers doubled in the Ark, partly because of the megamast – or heavy fruiting of native trees. Stoats and weasels are also believed to have increased in numbers.
With the support of Auckland Council, predator control was ramped up in the 2270 hectare Ark to try to protect the kōkako from the rising predator population.
Trees where kōkako nests were spotted were surrounded by a “ring of steel”, with traps every few metres.
"Despite the great work from our staff and volunteers, three nests were ravaged by predators.
"One nest had broken egg shells and rat droppings in it and none of the chicks we spotted successfully fledged."
Two kōkako chicks were banded, but then disappeared, says Mrs van den Broeke.
"We still hope to find some new kōkako that fledged in the Ark when we do our next bird count in August.
"Most years, we find a few young birds from nests we didn't know about," she says.
Kōkako vanished from the Waitakere Ranges in the 1930s and were reintroduced in 2009.
"We're doing everything we can to try to make sure they don't become extinct in the Ark all over again," says Mrs van den Broeke.
Three Forest & Bird staff and about 400 volunteers carry out predator control in the Ark.
The joint project between Forest & Bird and Auckland Council has 570 predator traps and 4800 rat bait stations.
Predators attacked five out of eight kōkako nests monitored in the previous 2018 to 2019 breeding season. Nevertheless, four kōkako chicks fledged in the Ark and its buffer zone in early 2019.
Mrs van den Broeke is asking Waitakere residents to pitch in with pest control efforts by putting traps or bait stations on their properties.
"The beautiful kōkako deserve every bit of help we can give them," she says.
For a high resolution photo by Luc Hoogenstein of a kokako, click this Dropbox link.