I have no idea what a whole bunch of them should be called, but "squabble" seems to describe their behaviour over some floating stuff in the river. Or perhaps given what is happening in our parliament since the ANC at last didn't get a victory at the polls, I should call these birds a "coalition of gulls"
Well certainly a squabble of seagulls is one term, according to Google. Another is colony of seagulls which is kind of boring. Yet another is flock of seagulls but that was appropriated by a New Wave band back in the 80's. The lead singer had a very strange hair style that was spoofed many times, notably by Chandler on Friends. Ironically the singer is now completely bald. So lets go with Squabble, that works best I think. Or coalition if you insist.
