Did a quick search for a rational reason even though TV and the genius of surprise or things in front of you you didn’t give much thought had significance from some producers like Hitchcock can make scared things fun they’re really not in real life lol Fires, sudden food from land fills fishing that got around to the birds, something going on in the ocean, what?
I guess gulls aren’t uncommon in your state. Their reaction might be but they could be unfamiliar with the territory, it won’t be just birds that will act up, most animals will including your pets. If your dog wants to run off and acting upset for instance.
http://wtfamidoinginidaho.blogspot.com/2011/06/why-hell-are-there-seagulls-in-idaho.html?m=1