Progress to Possum Eradication on the Otago Peninsula
Traps on the Otago Peninsula didn’t take a break over the Christmas period, with the team from Otago Peninsula Biodiversity Group’s Predator Free Peninsula project taking turns to attend call outs.
One possum was caught over the break, compared with six possums the Christmas before. Numbers are certainly heading in the right direction thanks to the hard work of staff, volunteers and contractors. 2022 will be another busy year of catching possums, each one getting closer to the last Peninsula possum!
Staff and volunteers are working out of the Otago Peninsula Biodiversity Hub in Portobello, which is open to the public on Wednesday afternoons.
In December and January, wax tags were put out to monitor progress towards possum eradication in Sectors 1 and 4. These small orange triangles feature a ball of non-toxic wax with a glowing tag. The glow tag is a visual lure that encourages possums to inspect whether the wax tag is edible by taking a bite. Each tag is left out for around a week and the number of bite marks gives an idea of how many possums are around.
A possum wax tag.
Sector 1 came back with the best possible result with zero bites! However, this doesn’t mean the battle is over. The detection network of trail cameras are still picking up possum activity at the top of sea cliffs. Footage shows possums learning to open the bait safe dispensers. These possums are likely too young to have been involved in our previous toxin operations there. The fact they have developed a taste for the delicious pre-feed made of non-toxic cereal suggests it will be easy to get rid of the last few possums in the future.
A map of wax tags in Sector 1.
Sector 4, the biggest operational area on the Peninsula, saw RTC values halved from monitoring before operations! RTC stands for “Residual Trap Catch” and it tells us the likelihood of catching a possum. For example, if you had 100 traps out overnight, what percentage of traps would we expect to catch a possum? Any value under 5% means possum populations are low, but we are aiming for 0%!
Monitoring shows the RTC value for the bulk of privately owned rural land on the peninsula is down from 2.67% in May last year to just 1.18% this year. It’s a great result, but there’s still work to do.
A follow up operation is planned for Sector 4 in April and the lean grid of traps will be rolled out across Sector 4, extending the existing network out from Sectors 1, 2 and 3.
Total possums caught: 20,954
You can help efforts to eradicate possums from the Otago Peninsula by reporting any possums you see — dead or alive! Email possums@opbg.nz with your contact information and details of your observation.