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Tracking tunnels containing ink pads and ''kill traps'' will be used to monitor rodent and stoat numbers as the department prepares to carry out the country's biggest 1080 poisoning programme.
The campaign is expected to cover an extra 700,000ha of the South Island at a cost of $21million over five years.
It is designed to protect native birds and bats by hitting rodent populations due to explode in number because of an unusually heavy fall of beech tree seed, which rodents feed on.
Planning is under way across the island, but the extent of the poisoning in each area will be determined by local monitoring.
Wanaka conservation services manager Chris Sydney said in the Mount Aspiring National Park preliminary data from seed monitoring showed a ''potentially moderate'' amount falling in the West Matukituki area but higher amounts in the Makarora area.
A clearer picture of seed falls at particular sites is expected when seed funnels are checked at the end of May and seed sent to Christchurch to be counted.
''So we are hoping, come June, we will have some data coming back from that.''
The deployment of tracking tunnels begins in the Makarora Valley this week, followed by the Young Valley next week and the West Matukituki Valley in the third week.
Raw data on rodent numbers should be available for analysis by the end of May.
Mr Sydney said the size of the area where poisoning was planned sometime between September and December had increased ''quite dramatically'' in the past two or three weeks.
The area had grown to protect more species - ''things like the rock wren that are at higher altitudes''.
He expected the area in the park would be finalised late next month.
Similar planning was being done in districts across the South Island.
The Battle for our Birds
Designed to protect populations of:
Great spotted, brown and tokoeka kiwi, kaka, kea, whio/blue duck, mohua/yellowhead, kakariki/orange-fronted parakeet, rock wren. Long- and short-tailed bats and giant snails are also included in the programme.