What animal hibernates in the summer?

Answer 1

Hibernation refers to the dormant state some animals go into to survive the

winter.

Some animals go into a dormant and bears state during the summer. This dormant state is

called "Estivation"

Answer 2

Snow birds.

Another answer--

This is called estivation, or aestivation, and it happens when the summer season is also an extremely dry season. According to Google, the following creatures estivate: some land snails, lady beetles (that's the name, not meaning female ones), many land crabs, North American desert tortoises, crocodiles (well, that's what they say. Not all of them, obviously), salamanders,cane toad, greater salamander, African lungfish, water-holding toad, Malagasy fat-tailed dwarf lemur, and East African hedgehogs.

I personally wouldn't bet that all of these things estivate all of the time. I'm pretty sure lady beetles are what most of us call ladybugs, and I've seen them in the summer. Crocodiles love hot weather, but maybe if their habitat dries up they estivate? For some others in the list, the Google article didn't sound too sure.