We have generic tests for the intelligence of birds.

Most famously used on Crows/Parrots, Seagulls are smarter than average and can solve some advanced puzzles, but they’re mostly below Corvids or Parrots. We’ve also tested their memory, they only care about food and can remember places they’ve gotten food and even the faces of people who they’ve got food from year to year, but we don’t think over too much longer periods.