Otago Peninsula Biodiversity Group community engagement team leader Marcia Dale said the anecdotal evidence was clear — 13 years of possum control was having an effect.
Locals were noticing over the last three years tūī and bellbird numbers had picked up significantly, she said.
And a statistical analysis of 14 years of bird monitoring, due to be completed this year, was expected to back that up.
"Preliminary findings suggest that the number of tūī recorded in the monitoring was up to four times greater in 2023 compared to 2011.
"It makes sense that we are seeing an increase in nectar feeders following possum control.
"As anyone who grows roses will know, possums love to demolish flowers.
"This not only decreases the food available for the animals that feed on nectar, it also severely reduces pollination and seed sources that would allow the habitat to regenerate."
To date 24,269 possums had been removed from the peninsula.
The work needed to continue; without the work to eradicate the pests locally "the remaining peninsula possums would build back up to plague proportions and we’d be back at square one".
A baseline number of birds had been taken in 2010, a year before possum control began.
Although the transects had changed over the years, there were more than 20 1 km walking routes across the peninsula used for counts.
Local volunteers, some of whom had been monitoring birds for more than a decade, were dedicated to the task.
In total, more than 5000 volunteer hours had been contributed to build up the data set.
Volunteers were trained and had recorded all the birds they had seen and heard.
The full dataset would be analysed by a statistician this year.
Although kererū numbers took a lot longer to recover, there were patches throughout the peninsula where the native wood pigeon were also on the rise.
"They need widespread landscape change to make a difference.
"So yeah, we are starting to see the signs that it is happening to them as well."
People could help tūī and bellbird numbers by planting kowhai and flax, Mrs Dale said.