Rodents knocked down in Waikaia Forest, Southland

The threat to native birds and bats from plague levels of rats, mice and stoats has been reduced in Waikaia Forest with a successful knock-down of rodents in a recent pest control operation in the area.

The Department of Conservation’s (DOC) Battle for our Birds operation over 7000 ha in the Waikaia Forest in August was targeted to protect threatened mōhua populations along with long-tailed bats/pekapeka, robins/kakaruai, yellow-crowned parakeet/kākāriki, hectors tree daisy, large land snails and peripatis/velvet worms.

Before the 1080 drop, there was significant beech seed-fall in the area and rapidly rising rat and mice numbers. Rat numbers were tracking at over 30% in August and were predicted to reach over 60% by November.

Monitoring results from 200 tracking tunnels show rat tracking rates are now 0.5% and mouse tracking rates 3%.

DOC staff have been making weekly checks in the forest and along river banks, tracks and roads in the operational area to remove any potential threat to public health, as part of consent conditions. Dead animals found included one deer, three possums and four non-native birds in the forest, and one possum, one hare, and four non-native birds on river banks.

Deer repellent was used over the entire block, in both the pre-feed (non-toxic) and toxic pellet drops.

DOC Southland Conservation Services Manager Ros Cole said this was a fantastic result that would allow native birds and bats to survive and breed this summer. Rat numbers will not climb again significantly for some time and the stoat population will similarly be suppressed.

“Now that the stoat plague expected this summer has been stopped, the remnant population of mōhua, which have only recently been rediscovered after an absence of 14 years, now have a real chance of hanging on and breeding well this summer in this isolated patch of beech forest,” Ros said.

President of the Gore and districts branch of the NZ Deerstalkers Association, John Howes, said branch members had looked around the operational area within the following weeks after the drop.

“To the best of my knowledge, none of our members found any dead deer,” John said.

“This is a good result as far as deerstalkers are concerned and the deer repellent seems to have done the job. Even with the addition of deer repellent, we were expecting to see a significant number of dead deer. We enjoyed open and frank dialogue with Cheryl at DOC and were pleased they took on board our concerns about the operation. We sincerely hope this programme will be effective in protecting the mōhua and long-tailed bats,” John said.

Meanwhile, there has been a full silver beech mast in the Catlins so a Battle for our Birds operation is planned there in coming weeks. Monitoring has shown rat numbers are rapidly increasing and are predicted to reach over 70% tracking levels. An important mōhua population is at risk from the predicted stoat plague this summer.

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