The Kaimai Range native forest is under threat due to the explosive growth of wallabies.
Forest & Bird says the government urgently needs to fund wallaby control, before the pest reaches plague proportions.
Wallabies could spread over a third of New Zealand within the next 50 years, unless control is increased dramatically, says Forest & Bird central North Island regional manager Dr Rebecca Stirnemann.
Wallabies eat native trees and plants in the undergrowth of forests and compete with native wildlife for food. They also damage tall tussock grasslands, leaving bare ground and increasing soil erosion.
“They are like giant rabbits that eat their way through native bush, reducing the species of plants and trees by 57 per cent,” says Rebecca.
“They pose an enormous threat economically and environmentally.”
Once forest undergrowth is gone, the thick spongy layer of the forest floor that usually holds water is at risk of drying out.
Populations of dama wallabies in the Rotorua lakes region are dangerously high and threatening new areas, she says.
“They pose a terrible risk to native forests in Te Urewera and the Kaimai ranges, which they are edging closer to as they expand in numbers.
“If they get established in those beautiful, mature forests, the consequences would be disastrous,” says Dr Stirnemann.
People have reported seeing 20 to 30 wallabies a night around the Rotorua lakes.
The small, grey dama wallabies can move long distances quickly and have just started spreading into Waikato for the first time, Dr Stirnemann says.
The Bennett’s wallaby weighs up to 18kg and eats six times more than a rabbit.
Dr Stirnemann says farms and forestry will also suffer if wallaby populations explode, because they eat large amounts of pasture grass and young pine trees.
Wallabies have already been sighted in fresh territories in Auckland, Northland, Hawke’s Bay, Gisborne, Wellington, Marlborough, Southland, and the West Coast.
If wallabies are allowed to spread without further control, the Ministry for Primary Industries estimates that in ten years they will cost $84 million per year in economic losses.
The current annual impact of wallabies is $28 million.
Effective control would cost about $7.4 million a year for ten years, says Dr Stirnemann.
In 2017 to 2018 only about $1.38 million was spent on wallaby control by local and central government and private landowners, she says.
“It’s shocking that we’re not putting more funding into dealing with this plague of wallabies that’s moving across both the North and South islands,” says Dr Stirnemann.
The two species of wallabies, dama and Bennett’s, were introduced to New Zealand from Australia, in much the same way as possums.