For the past two weeks, the birds has been sitting on eggs, and Brighton surf life-saver Gavin Murdoch said when unsuspecting beach users ventured too close, they were quick to let them know about it.
''It's pretty bold putting its nest right in the middle of the beach where it has.
''They do normally nest on beaches, but usually in remote places where there's no people or dogs,'' he said.
''They can be quite aggressive about defending their territory. They get up and give a squawk when you get too close.''
Pupils from Big Rock School had helped protect the nest by piling sticks up around it. Most beach-goers had been sympathetic to the nesting birds and had kept their distance, Mr Murdoch said.