Birds of prey have been used on a beach by a water company to try and stop gulls fouling bathing water.
Southern Water said it had evidence bird mess was affecting water quality along Worthing's beach on the West Sussex coast.
"Gull poo contains more bacteria than human or dog faeces," a spokesman for the water company said.
Tana Jackson said the seabirds appeared to be "extremely distressed" and called the scheme "ridiculous".
Southern Water said hawks were being used as a "visual deterrent" as part of a trial.
"We hope to continue this vital work later this month at Worthing and other beaches," the company added.
"However, before we continue, we wanted to gauge public opinion and over the next couple of weeks, take further samples of water quality.
"This will look for bird 'markers' - gull poo - and how it affects bathing water quality."
Ms Jackson said she saw two hawks being used to scare off the gulls.
"The seagulls in the near vicinity were extremely distressed and were flying and squawking around in a terrible state.
"I believe that this incident is the most stupid act I have ever witnessed," she said.
Last month Southern Water was hit with a record £126m-punishment for spills of wastewater into the environment from its sewage plants.
The water company said waste from dogs, birds and other animals could "seriously affect" the quality of bathing water.
"It's important we don't allow this on our beaches and to enter our bathing waters," the company's spokesman said.