Protective . . . The Department of Conservation says it is natural behaviour for nesting red-billed gulls to try to fend off "perceived threats" by diving at them. PHOTO: HAMISH MACLEAN

Oamaru is under siege by red-billed gulls.

The protected birds have been wreaking havoc in the North Otago town’s CBD during this year’s nesting season. There have been several reports of them repeatedly flying towards and dive-bombing innocent members of the public.

Department of Conservation Coastal Otago acting operations manager Craig Wilson said it was natural behaviour for nesting red-billed gulls to try to fend off “perceived threats” by diving at them.

“This is a defence mechanism displayed by many braided river birds, including oystercatchers, dotterels and wrybills,” Mr Wilson said.

But it would be unusual for them to make contact with people, so there should be no danger to members of the public, he said.

If people found themselves confronted by an angry gull parent, Mr Wilson said they should “keep moving through the area to minimise agitation to the birds”.

“People should not try to fend off or otherwise disturb the tarapunga [red-billed gulls],” he said.

The gulls should be nearing the end of their breeding season, so he expected the aggressive behaviour to stop in the “coming weeks” as most chicks would have fledged from the nest.

Oamaru’s central business district has been plagued by red-billed gulls creating an unwanted disturbance for several years. Theories as to why they started nesting in town vary, but most people believe it is connected to the closure of the landfill in 2017.

After several years of problem-level numbers nesting in the Coquet St area, the birds made a mass move to Lower Thames St last year.

Where they had nested on rooftops, Doc had worked with the council, building owners and contractors to minimise the risk of property damage and human health concerns, while still allowing the birds to successfully breed, Mr Wilson said.

“We have been impressed with the co-operative and understanding approach these building owners have shown and we feel we are getting good results..

“At the end of this breeding season we will review our successes and work with the council and building owners to improve how we jointly manage the situation.”

Waitaki Mayor Gary Kircher was aware of reports of dive-bombing gulls in the CBD, but said there was “really nothing” the council could do about it.

“We dislike it just as much as everybody else and all we can do is keep working away in the background to see what we can do with Doc,” Mr Kircher said.

The council would keep encouraging business and building owners to take proactive steps to prevent the gulls nesting on their buildings and make sure everyone was prepared for the next nesting season.

“It requires everyone doing their bit,” he said.

Red-billed gulls are a protected species and it is illegal to kill or disturb them. They have a conservation status of “declining” as their population is forecast to fall significantly over the next 30 years. Nationally, there are now fewer than 100,000 left.