In my backyard, the most mischievous one is the Blacked-capped Chickadee.
At this time, there are several of them coming to feed here. Here is one who is trying to find out how the hummingbird juice tastes like.
Does he like it?
"Yuck!! What kind of taste is this? I
like seeds and the suet, not this sticky water."
So he found out that never, ever he will be messing up with the hummer food.