Has anyone picked up on the intelligence of frogs, or bullfrogs in general? Is there something a little bit more about this frog's mental keeness and awareness?

I'm finding bullfrogs to have a sort of sharp intelligence. They respond to your presence readily, recognize your feeding times regularly; they'll croak as if calling to you if they know you're nearby,they will avoid predators by day without going in their water, bask in it at night, etc.

I have a little pond at my house, and I'm observing these critters. I don't know, but they're really dynamic creatures, have something far more in the sense of mental ability than other reptiles.