It was mired in controversy, protest and sabotage, but the Department of Conservation is hailing its 1080 drop on Northland forests earlier this year a huge success in eradicating pests.
In September DoC used helicopters to drop 1080 poison in Rakaumangmanga/Cape Brett and Russell Forest, but the operation was surrounded by protests from anti-1080 protesters and one of the helicopters being used was tampered with.
The aerial drop of 1080-soaked cereal pellets was intended to kill thousands of possums and other pests, and DoC says it is working.
DoC says rats in Russell Forest, located between Bay of Islands and Whangarei, have almost been wiped out and possum numbers have dropped to a fifth of what they were prior to the operation.
Pest numbers at Rakaumangamanga/Cape Brett, located in the Bay of Islands, have achieved similar results with no rats or mice detected and possum figures at a 10th of what they were before aerial 1080.
"These results show outstanding success and prove the effectiveness of aerial 1080 to control pests in a large area over a short period of time," Sue Reed-Thomas, DoC's Northern North Island Operation Director said.
"These low levels of pests have allowed the spring breeding of native bird life to have a higher chance of survival and the overall health of the forest will start to regenerate already. Native birds can produce more chicks, the ngahere can grow and provide kai to native birds, lizards and insects," Reed-Thomas said.
"Reducing the pests to such a low level is just the beginning of the work – DOC are committed to working with hapu and communities to keep these pest numbers low and bring back the kukupa, kiwi abundance and bring back other native species to the forests.
"We will continue to support the work of the Russell Roopu to implement the 20-year forest health plan, with the long-term goal of forest restoration. The use of aerial 1080 to restore the forest is the first step in the plan."
Tracking tunnels to count the number of pests have shown how effectively the poison had done its job.
Tracking tunnels are standard DOC practice to measure rat, mouse and stoat numbers in the forests. Tunnels with ink pads and bait are placed in predetermined lines at 50m intervals both before and after the 1080 operation. Staff then analyse the footprints in the tunnels to determine the presence of rodents. In Russell Forest DOC staff put out 160 tracking tunnels before and after the aerial 1080 operation. Before, 76 per cent of the 160 tunnels had pest interference. After, only one out of 160 tunnels had rat footprints.
Possum presence is measured through wax tags which are placed 20 metres apart and when possums chew the tags it indicates their presence.
Rats in Russell Forest have dropped from 76 per cent (+/- 4 per cent) to less than 1 per cent (+/-1 per cent). Possum figures were at 79 per cent and are now at 16 per cent (+/- 7 per cent).
Rakaumangamanga/Cape Brett pre-1080 monitoring showing 14 per cent rats, 17 per cent mice and 34.3 per cent possums. Post-1080 these figures are 0 per cent rats, 0 per cent mice and 4 per cent possums.