Perhaps they thought a cricket match was about to break out.
I have never seen nesting seagulls and Jimoin had a skit that stated they didn't have babies - they just appeared - fully grown. Plovers are also hopeless at nesting.
My sister and I visited an island off the coast of Vic once that had thousands of nesting seagulls. It was the first time I recall seeing gullets.
Only saw one baby. But seriously, the nests were everywhere, only a couple metres apart from each other, and often right by the side of the path...no way you could hold an orienteering event on Seagull Island in November!