This news was released by DOC 3 days ago. Here in Arthur's Pass there is a very close watch being kept on rat numbers by our Arthur's Pass Community Kiwi group using tracking tunnels. In the nearby Hawdon Valley, 10 km away, rat numbers soared this winter. 2 weeks ago DOC carried out an extensive and successful 1080 operation that has dealt to the rats in the meantime. But they will be back!
The key to the success of all this work is very close monitoring. You can monitor when there are beech flowering years. The seed is formed the following autumn and starts dropping onto the ground from early winter onwards.
Although beech "mast" years result in explosions in mouse, rat and stoat populations, they are also important for the breeding of native birds. All through this winter we have watched kea feeding on beech seeds in the tops of the mountain beech trees. Next to where I work here, 2 Yellow Crowned parakeets appear to be starting to nest in a beech tree hole. They are spending most of the day gorging on beech seed on the tree tips. Their breeding is very dependent on them being well nourished.
So there is the dilemma. Although the birds will get a boost from the abundance of beech seed and will then breed, this will not be successful unless the rat and stoat populations can simultaneously be much reduced by the aerial 1080 or other pest control operations.
These mast years are clearly both crucially important for the native birds and also crucially important for causing big build ups in predators.
We have to do everything possible to encourage the bird breeding and eliminate the predators.
DOC NEWS RELEASE:
Mast year creates rodent explosion
Date: 21 September 2009
Preparations are underway to use aerial 1080 operations to protect bats, mohua and parakeets from an expanding rodent phenomenon occurring at three West Coast sites.
An abundance of forest seed is boosting rodent numbers in many West Coast forests, but the Department of Conservation is very concerned about the impact this will have in the Landsborough Valley (South Westland), Maruia Valley (near Reefton), and in the Oparara Valley (near Karamea).
Acting West Coast Conservator Chris Hickford said monitoring confirms that extreme forest seeding, called a “Mast event” has occurred which is triggering a rodent population irruption.
Bats and parakeets and other bird species are at risk at all three sites and the Landsborough Valley is home to a significant mohua population.
“Rats in particular are deadly wildlife killers and in the past events like this entire populations of species, like mohua, have been wiped out,” Mr Hickford said.
“Our other problem is that increasing rodent numbers always boosts stoat numbers and if we don’t do anything to control the devastation the outlook for a wide range of wildlife in these important places is very bleak,” he said.
“We are going to move quickly now and we aim to get aerial 1080 rat control operations underway in each of these three sites by the end of October,” Mr Hickford said.
Most of the stoats present will also be killed by eating poisoned rats.
