Birdwatchers said Kittiwake nests on a key bridge in Scarborough had been cleared, leaving hundreds of endangered seabirds homeless.
North Yorkshire County Council said the bird deterrent gel was also added after concerns about feces damaging the Grade II-listed Spa Bridge.
The council said it consulted Natural England, which found it would not harm the birds’ larger habitats.
Bird watcher Nick Addey wants alternative nesting sites built.
Kittiwakes are a small species of gull that are on the conservation “red list,” and global numbers have dropped by 40% since the 1970s, according to the RSPB.
Mr Addey said nests can build up over the years as birds return to the bridge and build new nests on top of old nests.
“The nests can be about 10 inches tall, there are some large structures,” he said.
“You also get some newer breeding birds whose nests are smaller. [council contractors] They cleaned it all up and then glued these little tubes of fire gel that emit a UV light that the seagulls see like a flame so they don’t get close.”
Addey said a similar issue has been addressed near the Tyne Bridge, which connects Newcastle with Tyne and Gateshead, and artificial nesting sites – protruding towers – have been constructed to house displaced birds.
“This is a real opportunity for Scarborough – there’s no reason why they shouldn’t provide one of these towers next to the bridge.”
He said many people from the local birding community had complained to the municipality about the measures, but acknowledged that it was an issue that needed to be addressed.
“It’s a big issue for the Council, kittiwakes are increasing in the town but decreasing in the UK – so we’re all upset about that,” he said.
Karl Battersby, corporate director of business and environmental services for North Yorkshire County Council, said the impact of the measures will be monitored.
“Before we started, we had an independent habitat assessment done, as we should rightly do, and consulted with Natural England. The conclusion was that the action would not harm the birds’ larger habitats.
“The work was planned to avoid a time when birds would be present on the bridge. It involved cleaning up old nesting material and droppings, treating them with disinfectant, and placing small optical gel containers on the ledges.”
“This method was chosen over mesh or electric deterrents because the mesh risks entangling birds and is unsightly.”
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