The swelling birdsong on Otago Peninsula is music to the ears of Dr Ursula Ellenberg.
The Otago Peninsula Biodiversity Group co-ordinator is in the mood for celebration, as annual spring bird counts are showing upward trends in bird numbers.
From September to November, volunteers regularly visit 20 1km sections of the landscape, from the start of the peninsula to its tip, listening carefully for bird song and cataloguing what they hear.
"Our committed volunteers have been going out since 2013, and are excited at the return of birdsong from a variety of species, including tui, bellbirds and grey warblers,'' Dr Ellenberg said.
There was also evidence that kereru (wood pigeon) numbers were increasing, although their quiet calls meant they were tricky to identify, she said.
While it was difficult to catalogue exact numbers of birds, it was clear the efforts of the biodiversity group to remove possums from the peninsula were paying off.
In the seven years since the group began, volunteers and landowners had removed about 16,600 possums from the peninsula, leading to a gradual recovery of the tree canopy and increased habitat and food sources for birds.
"We had a big push over winter and removed quite a few more - we have really cleared out the large Department of Conservation reserves in the past two years,'' Dr Ellenberg said.
"There are still pockets of possums, but it is looking good.''
The possum trapping had moved steadily towards the peninsula's gateway - around Waverley and Vauxhall - which would become increasingly important in preventing the return of possums, Dr Ellenberg said.
"We have a fantastic group of peninsula guardians, co-ordinated by Kate Tanner, who are really enthusiastic about defending the peninsula.''
More guardians were needed to contribute to this vital work, Dr Ellenberg said.
• To mark Conservation Week, the Otago Peninsula Biodiversity Group will hold a trapping workshop on Sunday, from 1pm-4pm at the Grants Braes Football Club, at 260 Tomahawk Rd, Tomahawk.
BRENDA.HARWOOD @thestar.co.nz
