“Forest monitoring has confirmed that about a million tonne of seed has dropped in this year’s beech mast and that this has triggered a plague of rodents of biblical proportions. These seeds will soon germinate leaving hordes of starving rats and stoats that, if not controlled, will go on to kill millions of our native birds in spring and summer,” Dr Smith says.
Seven thousand predator tracking tunnels and 430 seed collection trays have been monitored by the Department of Conservation (DOC) over the past four months. The rat population has exploded by fivefold from about three million to about 15 million, and is projected to increase to 30 million. An increase in stoat numbers which pose an even greater risk to native birds is expected, with the numbers estimated to grow to about 25,000.
Pic: David Hallett
“We cannot ignore this science and let our treasured endangered birds like kiwi be annihilated by this plague of rats and stoats. That is why we are proceeding with our ‘Battle for Our Birds’ programme of pest control that targets the worst infected forests and where our endangered birds are most at risk. The operations in 29 forests totalling 708,000 hectares have been confirmed. These operations will be carefully timed relative to pest monitoring data and weather to maximise the conservation benefit. They will begin this month and be completed in November. A further 14 forests covering 200,000 hectares are on close watch and will also have pest control operations if monitored predator numbers exceed thresholds,” Dr Smith says.
Dr Smith outlined the ‘Battle for Our Birds’ programme in his annual speech to the Rotary Club of Nelson in January this year, and at the time said the final programme would be determined after forest monitoring data had been collected. Some new areas have been added, such as D’Urville Island in the Marlborough Sounds, some expanded like in the Kahurangi National Park, and some may not proceed due to pest count numbers not yet reaching thresholds.
“These pest control operations cover a record area and involve a mix of aerial and ground control using toxins and traps, depending on the topography and practical logistics. It does involve the use of aerial 1080, but does not mean record use of the toxin. Pre-feeding, improving bait quality to avoid crumbs attractive to birds, helicopter rather than fixed-wing aircraft distribution, GPS, and the development of repellents for non-target species have enabled major improvements in 1080 control methods. Bait application rates have reduced from 30 kilograms to one kilogram per hectare. Deer repellent is to be used in the Cobb Valley in Nelson and Waikaia in Southland to avoid by-kill within deer herds that are of particular importance to the New Zealand Deerstalkers’ Association.”
The cost of this 500,000 to 700,000 hectare pest control programme this year is between $9 million and $12 million. In addition, TBfree New Zealand carry out another 300,000 hectares of pest control work on public conservation land that is being coordinated with DOC to maximise the benefits to native species. A record total of one million hectares of pest control is expected to be undertaken this year including normal operations. ‘Battle for Our Birds’ also involves DOC increasing its ongoing pest control work from the historic rate of 150,000 hectares per year to 450,000 hectares per year and has a total budget of $21 million over five years.
“I know some people are opposed to the use of toxins but we have to back the science if we are to save our native birds from extinction. The programme is particularly focused on ensuring the survival of the great spotted, brown and tokoeka kiwi, kaka, kea, whio (blue duck), mohua (yellowhead), kakaraki (orange-fronted parakeet), rock wren, long and short tailed bats, and giant snails. It will save millions of other native birds like fantails, robins, tui, kereru, riflemen, bellbirds, tomtits and warbles, reptiles like geckos, insects like weta, trees like rata, and plants like mistletoe.
“Our kiwi will not exist in the wild for our grandchildren if we do not act now. This programme is about backing our kiwi, kaka and kea and killing the rats, stoats and possums that threaten their survival,” Dr Smith concluded.
Pic: Nga Manu Images