Organic waste entering Dunedin’s landfill supports thousands of southern black-backed gulls as well as other species at the site.
As a condition of consent for the city’s next landfill — planned for Smooth Hill, near Brighton — the council is working on a gull management plan to reduce the risk of bird strike at Dunedin Airport before the closure of Green Island, expected about the end of the decade.
But when Dunedin’s new kerbside waste collection system takes effect in July, organic waste will be separated from the general waste stream — and a large part of the about 200tonnes of organic waste a week that now goes to the tip will be exported north to Timaru for disposal there before processing facilities are established here.
Asked whether birds at that time would begin to leave the landfill and whether the risk of bird strike would increase at Dunedin Airport, the council took two weeks to respond and did not answer the question directly.
"We expect some birds will remain at Green Island following the introduction of the kerbside collection service," a council spokesman said.
"The draft [southern black-backed gull] management plan currently being developed will include appropriate management techniques to address any risk that may result from a reduction of birds at Green Island landfill."
The plan was being developed in collaboration with Dunedin Airport, the spokesman said. He confirmed monthly baseline bird monitoring by an ornithologist began in January 2022 and was ongoing, as required by the Smooth Hill landfill consent conditions.
However, data was still being collected and so the council could not yet provide any findings, he said.
From July, food scraps and garden waste collected as part of Dunedin’s new kerbside collection service would be taken by EnviroNZ to the new Green Island "organics receival building", now under construction.
"As part of our wider plans for the resource recovery park at Green Island, we are also seeking resource consent from Otago Regional Council for the construction, operation and management of composting processing facilities.
"We expect these facilities to be operational in 2025 ...
"Until then, organic waste will be trucked to a composting facility in Timaru."
How much organic waste was diverted from the landfill would be studied once the new collection system started, the spokesman said.
A draft of the gull management plan from last year said in July 2022 a high of 8320 gulls were counted at Green Island.
A Dunedin Airport spokeswoman said the airport was comfortable with the council’s response.
