But the Department of Conservation (Doc) says it is for business owners to deal with.
As reported by the Oamaru Mail in July, there were significantly more red-billed seagull nests found in the CBD during the 2023 breeding season than the year before.
The gulls are indigenous and a protected species.
Doc coastal Otago operations manager Gabe Davies said a national survey between 2014 and 2016 found there were more than 27,000 red-billed seagulls nationally.
"However, they are classified as nationally vulnerable because their numbers are decreasing at an alarming rate."
Their roof nesting habits were for individual business owners to deal with, he said.
John McKenzie, who owns three CBD buildings affected by seagulls, said it was not that easy.
Nets did not work on pitched roofs as "the net just lies on the roof and the seagulls end up sitting on top of that".
"We’ve been through everything, all the recommendations," Mr McKenzie said.
He had installed bird spikes on roofs, which had been "moderately successful".
"It has reduced the quantity of birds sitting on our buildings.
"It hasn’t stopped them.
"In one area they’ve actually nested on top of the bird spikes, so that’s not much help."
Mr McKenzie said he had spent "eight or nine thousand" dollars to prevent nesting gulls.
However, the 10 CBD buildings owned by the Waitaki District Council have remained relatively gull-free.
The Forrester Gallery roof now had netting to deter pigeons and the Oamaru Library had spikes.
The netting had cost the council over $13,000, while maintenance staff spent hours each week clearing gutters and bird droppings, property manager Grant Rhodes said.
"Around nesting season they spend more time clearing nesting material.
"Sometimes this is daily."
Mr Rhodes said there was not much the council could do about the seagulls.
However, he commended building owners’ efforts to move the seagulls away from the CBD.
