Rat numbers have tripled on New Plymouth's popular Coastal Walkway this year, posing a threat to kororā/little blue penguin, but experts say the long-term trend continues to be downwards.
TRC senior ecologist Halema Jamieson (right) laying rat tracking tunnels with volunteers Naomi Dowding-Smith and son Declan in Pukekura Park. Photo: Supplied / Taranaki Regional Council
In an annual survey carried out in April, rats were detected at 17 percent of tracking tunnels in the city, up from a record low 9.8 percent last year.
This was still significantly less than the 33 percent in 2018, when Taranaki Regional Council launched the Towards Predator-Free Taranaki programme.
But a particular area of concern however was the coastal walkway site near Bell Block where rat tracking rates had tripled from 10 percent in 2018 to 30 percent this year.
Programme lead Sam Haultain said with so many people using the walkway, there was plenty of food available for rats which had bolstered their population and reduced the effectiveness of traps.
"There are traps along the walkway and we are working with the New Plymouth District Council to improve their efficiency, given the availability of other food resources.
"A lot of wildlife lives in and around this area, including the precious kororā/little blue penguin, which makes this even more important."
Haultain said the general increase in tracking rates this year was no surprise.
"We've had amazing weather over the last year or two, which rodents love.
"They have plenty of food and it has been warm, so last year was always going to be hard to beat.
"Keeping the rate at 17 percent is testament to the community's awesome trapping effort and just motivates us to keep on going."
Haultain said overall, the figures were encouraging.
"The good news is just one of the 10 sites tracked higher this year than at the start of the programme, with six lower and three showing no change."
Each April since 2018, Towards Predator-Free Taranaki has monitored rodents at 10 sites across New Plymouth city.
At each site 10 tracking tunnels are baited with peanut butter and left out for one fine night. In the morning, prints in the ink reveal whether there were rats, mice or other creatures present.
Haultain said Towards Predator-Free Taranaki and NPDC would use the monitoring results to target problem areas.
These included sites at Herekawe Stream, Centennial Park, Huatoki Domain, Brooklands, Pukekura Park and Karina Rd, where active volunteers looking after trapping networks.
They would also learn from and build on the gains made at several public areas across the city.
In urban areas, Towards Predator-Free Taranaki had to date focused on rats, as they did the most damage to native birds, lizards and biodiversity and were a target species for the Predator Free 2050 goal, Haultain said.
More than one in five New Plymouth households had a rat trap in their backyard and NPDC maintained trapping networks throughout public parks and walkways.
The urban team had also widened its focus to include possums, destructive predators that were known to live in New Plymouth and other towns, Haultain said.
Subsidised, humane traps were available for those who wish to set and maintain them in their backyards, she said.
For information about volunteering or trapping contact pftaranaki@trc.govt.nz or follow Towards Predator-Free Taranaki on Facebook.