English Nature has objected to the proposed renovation of Brighton's West Pier, saying the plan would not protect starlings and birds of prey.
The wildlife watchdog said proposals to protect the starling roost in the planning application submitted by developer St Modwen and the West Pier Trust, were inadequate.
Conservation officer Roger Matthews, said the application's environmental statement was "unimaginative and vague" and lacked ecological detail.
He said the modifications needed to protect the birds would not be costly or obtrusive and added there was a strong possibility the starlings would go elsewhere in the city if the roost was lost, causing serious pollution and damage.
The developers should provide at least two nesting boxes for peregrine falcons which prey on the flocks of birds the watchdog said.
Measures to protect marine life should also be a condition of any planning permission.
The developers recently unveiled revised designs for the rebuilt pier, after seafront buildings in the original proposals, were branded too intrusive.
The national lottery is providing £14 million towards the £30 million renovation project.
Rachel Clark, general manager of the West Pier Trust, said: "We are aware of the concerns and we have no intention of ignoring the needs of the starlings but, on the other hand, the restoration is our main concern."
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