Personally, I think it might be the other way around: The hummers might be sizing up the crows!
They are feisty little warriors. You never want to let one of them get into your house. They will dive at you peck you! I know -- any
bird would do that if suddenly made "captive," but hummers are notoriously aggressive.
Blue jays are mean & rude, but they will take it upon themselves to warn all birds (regardless of type) within earshot of a predator in the vicinity. That sort of makes up for their bad attitude.