Seagulls eat clams. They break the shells by dropping them onto rocks from a height. They're able to learn to steal food from other birds when they see a chance, and conversely, to regulate from which height to drop clams of different sizes.
All of these require planning and risk assessment abilities. Being able to take a bag of potato chips away from human-infested buildings and opening it is not really that far outside the scope of their adaptations.
A few years back I was walking along the SF bay down in the marina with a friend when suddenly I heard a "clunk" and felt a splash of water on my legs. Initially I thought some drunk idiot threw a beer bottle out the window of their car, but a few seconds later a Seagull swooped down, grabbed a clam it had dropped from who knows how high up, and fly off with lunch. I had no idea they did that, I just stood there dumbfounded for a few seconds.
All of these require planning and risk assessment abilities. Being able to take a bag of potato chips away from human-infested buildings and opening it is not really that far outside the scope of their adaptations.
Still, crafty little bastards they are indeed.