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He says DOC knows where the most vulnerable populations are and has to gauge how much pressure they will be facing from rats and stoats. Peter says that deciding where to focus aerial 1080 predator control is essentially triage. So if we don’t control those pests prior to roughly the end of this year, it’s too late.” Triage “A lot of the impact we are trying to stop occurs through the spring and summer months, when rats and stoats, in particular, are busy chewing their way through birds’ eggs and nestlings. Peter says that time is another significant constraint. There’s only so many skilled helicopter pilots able to do this work.” There’s a pool of contractors out there who are experts in this field, but there’s only so many of them. “Money is one of those constraints, but we also actually run out of skilled people to do this work. “We are aiming to pretty much run at the limits of New Zealand’s current predator-control capacity. More money is not the simple answerįorest and Bird has been in the news recently saying the DOC needs more money so it can apply Tiakina Nga Manu across a larger area than one million hectares.īut Peter says the limitation he faces is not just funding. Peter says that evidence collected so far this year suggests that about 1.4 million hectares of vulnerable conservation land will have significant seed fall and predator plagues.Īs the mast progresses, Peter and his team will begin to prioritise which areas are most in need of predator control, and when the best time is to treat each one. They are also using rat tracking tunnels on the forest floor to find out how many rats there are in different forests. “So far everywhere they’ve looked they’ve found extremely high number of seeds being produced,” says Peter. “As soon as we got through the 2018 summer we had warning bells ringing that ‘hello – it looks like we’ve got a mast coming’.”įollowing the mass flowering seen this summer, DOC staff have been using helicopters to collect branches of beech trees from likely problem areas to see how heavy the seed set has been. “This one’s looking like a doozy,” he says. He is currently planning the department’s largest response to date, which will cover up to one million hectares of forest. Peter Morton co-ordinates the Department of Conservation’s predator control programme. Previous Battle for our Birds programmes have been very effective in controlling pests and boosting bird numbers. These operations are branded Tiakina Nga Manu – Battle for our Birds, and focus on protecting populations of rare, vulnerable species such as rock wrens, orange-fronted parakeet, mohua, and long-tailed and short-tailed bats. Photo: RNZ / Alison BallanceĭOC began carrying out large scale predator control operations using ground control, such as bait and traps, as well as aerial 1080, in response to large mast years in 2014, 20. Scientists have been measuring seed fall in hard beech forest in the Orongorongo Valley for 50 years. In a 2016 Climate Change Impact report by Barron et al, for example, the authors modelled various ICPP climate scenarios (RCPs) and concluded that “in the long-term (to 2100) the frequency of mega-masts is not predicted to increase significantly under any RCP scenario.”

This is because the delta-T model reflects a relative temperature difference between two years, rather than absolute temperatures.įurther modelling work on the effect of increasing temperatures on the frequency of mast seeding years has found no significant effect. In the original delta-T scientific paper, published in 2013, lead author Dave Kelly, a botany professor at the University of Canterbury, whose long term work on mass flowering led to the creation of the delta-T model, wrote that warming temperatures will not cause more frequent mast years. Will climate change cause more frequent mast years? Models suggests ‘no’Īn apparent increase in the frequency of mast years has led to concerns that they may become more frequent or more widespread as climate change increases average temperatures. In most other places, they occur every four to five years. The West Coast of the South Island is particularly prone to mast seeding events, with one occurring on average every three years. Work by Landcare Research scientists looking at 40 years of data has shown that most mast years are localised and cover less than 10 percent of the beech forests.Ī mega-mast is one that affects more than half of the beech forests, and over a 25-year period there has been an average of 5.2 mega-masts. Southern beech forest in North Canterbury.