Brian Bullough
DIGIDOPE
I notice the tinyfishy link in post #1, one GBB has yellow legs and one pink are there different races ,variations.
I've seen Western Gulls do that.
I think its unfair of you to compare a G BB Gull to a Raven. GBB Gulls are much more powerful - they can hunt larger prey items on their own, they can defend their prey or carrion against 3-4 Ravens with ease. Ravens on the other hand scavenge more.
I had heard of Ravens in groups trying to kill Hares and succeeding but if a Hare can kick a Goshawk and make it remember for life what it did, then Im sure it could do more to a Raven.