Pest control expected to boost tui survival rates

A bumper tui breeding season is expected at Environment Waikato’s Hamilton Halo project sites this spring, thanks to highly successful winter pest control operations.

That could mean a big jump in the number of tui visiting Hamilton as early as next winter.

Environment Waikato is aiming to bring more tui to Hamilton by wiping out the tui’s two main predators – ship rats and possums – at forested breeding sites near the city.

It is currently controlling the pests at one Whatawhata site and two sites near Cambridge, Maungakawa Scenic Reserve and Te Miro Reserve. In total there are 850 hectares of native bush under protection.
Environment Waikato had to devise a special pest control programme to kill the rats, which are hard to eliminate because they have a small feeding range of only 100m. This meant many bait stations – more than 1300 – were needed across the three sites.

Pest control took place over August and September, prior to the October tui breeding season.
This week a “rat census” was carried out to check the success of the operation, using small tunnels with inked cardboard floors, which record rat footprints.

“The results were excellent, with only 2.2 per cent of the 225 tracking tunnels registering rat footprints, compared with up to 41 per cent before pest control,” Environment Waikato councillor Paula Southgate said.
“With the rat and possum populations now very low, estimates from Landcare Research are that nesting success could increase from around 25 per cent to 75 per cent easily.

“There were also reports that native seedlings are flourishing on the forest floor without possums and rats around to gobble them up.”

Other native birds, such as kereru and bellbirds, will also benefit from the pest control.