Nature Bunnies have the Crush skill, enabling them to destroy any building and units on tiles they move to. Just like any other unit, Nature Bunnies can attack, kill, and be killed. Also, although Nature Bunnies can enter cities, they cannot capture cities. Moreover, Nature Bunnies cannot be converted with Mind Benders, as they do not belong to any one tribe. (Nature Bunnies cannot be controlled by any human player.)
Spawning many Nature Bunnies has previously been known to cause a variety of glitches that can be resolved by exiting and reopening the game.