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Dairy Flat businesses say a worsening influx of gulls is damaging property, while coliform bacteria have been detected in rainwater tanks beneath heavily fouled roofs.
During the week, hundreds of gulls flock to roost on commercial buildings near the intersection of Kahikatea Flat Road and Dairy Flat Highway, leaving roofs streaked with droppings and gutters clogged with feathers, chicken bones and other waste. Businesses have noted that the gulls tend to be absent outside of landfill operational hours.
They believe the gulls are feeding at nearby Redvale Landfill, operated by Waste Management NZ (WMNZ) They say the problem developed during Covid lockdowns, but has become markedly worse during the past six months.
Their concerns have taken on added significance following two confirmed detections of H5 bird flu in New Zealand last month. There is no evidence that the Dairy Flat gulls are infected, and Biosecurity New Zealand says there have been no further detections since July 17. However, birds that congregate in large groups are among those given priority in national surveillance.
Caltex Dairy Flat manager Kay Spago says gulls on the service station roof are creating problems for customers parking below, as well as raising concerns about the quality of the business’s tank water.
At Silverdale Panel Beaters, owner Nick Smith says the rainwater supply has been disconnected and fresh water must now be brought in.
“We find chicken bones and all sorts of waste from the tip in the gutters and have to clean them regularly,” he says.
“It’s so bad we can’t park our cars outside without risking damage from bird droppings, which is difficult for us and our customers.
“On a bad day you can’t see my roof. It’s completely covered.”
Neighbouring business The Workshop has also stopped using its tank water after tests detected coliform bacteria.
Owner Anton Nairn says as the business restores classic cars, they cannot risk corrosive droppings damaging vehicles. Courtesy cars have to be washed daily, while bones, feathers and droppings get caught in the gutters.
He says the affected businesses are each paying hundreds of dollars for water deliveries and believes WMNZ should contribute to preventive measures and clean-up costs.
“It would be nice to find out what has caused this and what Waste Management will do to eradicate it,” Nairn says.
Further down the road, blocked gutters at roofing company GAF caused water to back up and flood the premises earlier this year.
Manager Jeremy Probett says feathers, bones and other material carried by the birds had clogged the drainage system. The business paid to bypass its contaminated water tanks and is now spending hundreds of dollars each month on delivered water.
Although fake owls placed on the roof worked briefly, the birds quickly became accustomed to them. “It might seem like a weird or funny issue until you realise the widespread damage its causing,” Probett says.
The Redvale Environmental Protection Society has formally asked Auckland Council and WMNZ to commission an independent investigation.
Society chair Nick de Witte says the effects extend beyond nuisance concerns and raise questions about public health, workplace safety, building compliance and whether WMNZ’s bird-management measures are effective.
The organisation has asked for an independent investigation, a written report, a timetable for corrective action and immediate measures to reduce bird numbers and off-site effects.
An ecological assessment prepared for the proposed Redvale landfill extension confirms that the site attracts large numbers of birds.
The November 2025 report recorded morning peaks of more than 1000 common mynas and 275 red-billed gulls. Southern black-backed gulls were less abundant but frequently observed.
It identified food available at the active tip face as a key driver of bird activity. Records showed 13,842 birds were culled between 2019 and 2025, with culling activity increasing from 2022.
Its pest-bird plan sets management thresholds of 400 mynas and 20 southern black-backed gulls, with additional action required when those levels are exceeded.
But the rapid escalation has led businesses to question whether something about the food waste at Redvale has changed.
University of Auckland marine sciences professor Andrew Jeffs says gulls are opportunistic, communal feeders with a strong sense of smell.
“What’s probably happened is that they have found an abundant food source, close to great roosting sites.”
A WMNZ spokesperson says Redvale has operated for more than 30 years and uses bird-management measures that are standard across the landfill industry.
“Based on our monitoring, we have not seen an increase in bird numbers at the landfill or any changes to our operations that would explain reports of increased bird activity in the Dairy Flat village area,” the spokesperson says.
The company says bird behaviour can be affected by seasons, weather, food sources and changes in the surrounding environment. It will continue monitoring the landfill and review its measures where opportunities for improvement are identified.
However, the November assessment identified food available at the active tip face as a key driver of bird activity at Redvale.
Auckland Council licensing and environmental health general manager Robert Irvine says his team has been in discussion with WMNZ regarding the concerns. He says WMNZ is required to proactively manage pests on its site under its resource consent conditions. This includes bird population surveys and, where appropriate, culling non-protected bird species.
“Red-billed gulls (the species shown in the image) are protected under the Wildlife Act 1953 and in decline,” Irvine says. “WMNZ must minimise the impacts of pests on the community but also comply with wildlife protection laws. We are seeking further advice from DOC.”
Irvine says council will continue to work with WMNZ to minimise the impact of pests on the community.
However, neither response indicated that an independent investigation of the affected properties would be done.
For the businesses, confidence that the plan is being followed offers little relief. Although WMNZ says nothing has changed at Redvale to explain the increase, they say the evidence is written in bird droppings across their roofs.
