It doesn't take a lot of effort to research potential predator/competitors for seagulls and then hold trials on what works. There's a lot of options, and if the gang doesn't seem intimidated by your choice of predators, invent one.
I'm sure this would be a very interesting project for any student!
Unless you're reintroducing a native species to the area or providing habitat for existing-but-endangered species, you're probably going to raise the wrong kind of eyebrows with that kind of research.
These researchers say they're rooting for the birds after all.
Humans have a long history of solving small problems by introducing bigger problems re: introducing non native species.
I'm sure this would be a very interesting project for any student!