There has been a 20% increase in bird numbers on Otago Peninsula in areas where possum eradication work has been done.
Preliminary analysis of monitoring data collected by the Otago Peninsula Biodiversity Group and University of Otago ecology students has confirmed what many residents believe - that bird numbers are increasing.
Botany department ecology senior teaching fellow Dr Haseeb Randhawa said students analysed the 25,000 bird observations recorded by the biodiversity group plus the monitoring work they did themselves.
Given increasing bird numbers was an objective of the biodiversity group, it was positive news.
''While it's still early, only three years on, their efforts are paying off.''
No seasonal pattern was seen, which indicated the numbers were not due to migrating birds.
''We're confident the increase in bird abundance is due to the possum control.''
As well as using tunnel tracks to detect remaining possum and rodents. as the biodiversity group did, the students also used chew-track cards.
''The chew cards were more effective at detecting possums, regardless of the type of vegetation.''
While tunnel tracks were more effective in picking up rodents in most areas, in certain types of vegetation chew-track cards showed more.
''We need to do more study on the type of vegetation before we rely on chew cards or tunnel tracks.''
In the areas closer to where there had not been any control, students found bird numbers showed no apparent trend.
Biodiversity group project manager, Cathy Rufaut said getting the first hard data showed the importance of the group's monitoring work.
While having the data was critical to accessing funding for their work, it was also important for communities around New Zealand watching the group's work and wondering if it could be done in their neighbourhoods as well, she said.
The group hoped to secure funding this year to begin monitoring lizards and insects alongside the birds and vegetation, to gather baseline data before rodent eradication work began in the next few years.
Dr Haseeb Randhawa said he hoped to be able to continue the work with next year's students, as feedback from this year's group indicated the practical ''real life'' experience was valuable and appreciated.