Feral cats that dine out daily on native species including long-tailed bats, kea and rare giant skinks are now threatening to add treasured takahē to the menu
Like a colourful rotund hen the flightless takahē is just not wired to protect itself from mammalian predators.
Having evolved without their presence, the birds are unwary and the odds could favour a large cat should push come to shove.
Takahē are classed as a nationally vulnerable threatened species with a high risk of extinction in the medium term, according to the Department of Conservation.
Nine breeding pairs of the prehistoric-looking birds were released last month on Ngāi Tahu-owned Greenstone Station near Glenorchy.
Trapping and monitoring of feral cats in the area has been ramped up but a risk remains, particularly as few takahē populations have previously been rehomed within range of potential predators.
“Feral cats will be a risk to the takahē in the Greenstone Valley but we don’t know exactly how vulnerable takahē are to cat predation,” says DoC project lead Jason van de Wetering.
Ferrets are a bigger worry but van de Wetering says if an individual cat learnt takahē were viable prey that could change.
DoC has 26 cat kill traps spread across the valley. Those are in addition to the Routeburn-Dart Wildlife Trust and Southern Lakes Sanctuary’s 27 traps in the surrounding area.
Night shooting is also used against the valley’s predators, which are watched from every angle by a grid of 65 trail cameras spaced every 500m.
“We normally see four to six cats when we run the cameras,” van de Wetering says.
Predators havoc
Southern Lakes Sanctuary, formed by the merger of a number of small voluntary Queenstown-Lakes conservation groups, has recently joined the war on predators.
Takahē are potential newcomers on a list of native species getting hammered by feral cats across their 660,000ha patch.
The group say all is not what it seems among the much-photographed sparkling rivers and snow-capped peaks surrounding lakes Wānaka and Whakatipu.
Rather than being places of refuge and safety for indigenous wildlife, the forests, riverbeds and high country are overrun by introduced mammalian predators. Many native species cling on in isolated relict populations.
Southern Lakes Sanctuary biodiversity co-ordinator Greg Whall says kea, river birds and long-tailed bats are on the diet of feral cats in the pristine mountain terrain at the head of Lake Whakatipu.
He says monitoring and control work around Glenorchy shows feral cats inhabiting all remote areas visited, with 14 of 18 trail cams recently snapping images of felines over a three-week period.
“With our partner group Routeburn Dart Wildlife Trust we’ve removed more than 150 feral cats from the valleys on the Glenorchy side of the lake in the past 12 months and there are still plenty around,” Whall says.
Wrybill, black-fronted tern and dotterels regularly fall prey to cats in the riverbeds and other native-bird and reptile species succumb in the surrounding forests.
Dotty about dotterels
Rabbits have been the staple diet of feral cats around Lake Dunstan, near Cromwell, for decades.
Near the head of the lake, luxury homes overlook the 27ha Mahaka Katia Scientific Reserve where migratory banded dotterels breed the the spring.
The birds end up supplementing the cats’ diet and eggs and chicks are vulnerable to a range of predators.
This spring the new owner of a nearby gravel pit, Winstone Aggregates, has donated $8000 to a group of residents keen to help DoC catch ferrets, stoats, rats, hedgehogs and cats in the reserve.
The predators are thought to be the key cause of a decline in banded dotterel populations nationwide.
Botanist, orchardist and dry-gardening guru Jo Wakelin says she’s grateful the alluvial terraces haven’t been swallowed up by orchards and lifestyle blocks so they continue to provide a home for birds and rare plant species.
DoC targets cats with a trap line but Wakelin and two neighbours reckon more traps and more people-power are needed to give the birds a real chance.
Calling themselves the Dotterel Band, the trio have bought traps that send a signal to a cellphone when sprung.
“The dotterels were here before we were so I feel we need to help them,” Wakelin says.
“We’re hoping more neighbours along the lake will join in once we’re set up.”
Felines keep on coming
Nearly 500 feral cats have been caught in one year at Macraes Flat about 80km north-west of Dunedin.
The attractions for the predators include two rare giant skink species found in the DoC-managed Macraes Conservation Area.
Otago and grand skinks today occupy just 8 percent of their original range but populations are holding on thanks to prolonged pest-control efforts.
DoC targets feral cats, stoats, ferrets, weasels and hedgehogs across 4500ha of conservation and privately owned land.
“The aim of trapping in the wider area is to target the full range of introduced predators to stop them dispersing and reaching the core protected areas, which also include predator-proof fenced areas,” says DoC Central Otago operations manager Nicola Holmes.
“Over the past 16 years trapping at Macraes has caught an average of 303 cats a year.”
The work is paying off for both skink species whose conservation-threat status was downgraded from “nationally critical” to “nationally endangered” within five years of management starting.
Holmes says it’s unclear whether cat populations are increasing but it is evident that newcomers are constantly coming into the target area.
Cats slink out of sight
Yet not all pest controllers have cats on their hit lists.
Otago Regional Council, as pest overseer for the region, identifies feral cats as a threat to biodiversity values in “site-led programme” areas at Otago Peninsula, West Harbour, Mt Cargill and Quarantine and Goat Islands in Otago Harbour.
Before introducing its pest-management plan in 2019 a cost-benefit analysis determined felines didn’t warrant inclusion as pests other than in the site-led programmes, where the only rule is a prohibition on the introduction, holding, enclosing or otherwise harbouring of feral cats.
Council environmental implementation manager Libby Caldwell says the pest-management plan is not due for review for another six years.
Meanwhile the Government’s Predator Free 2050 Strategy and first five-year action plan launched in 2020 exclude feral cats as a pest species.
DoC will lead the first review of the strategy next year and the public will have a chance to say whether feral cats should be added to the pest hit-list.
Inclusion would translate to funding and support for control work.
Made with the support of the Public Interest Journalism Fund
