Grab a shovel, because we're digging in to see some animals with real underground cities. But who has the most complex subterranean home? Find out in this top 10 countdown. From a bird that creates a hole for its home by flying head first into a cliff to an insect whose excavating can be heard a mile off, discover that there's more to digging than a hole in the ground when digging is taken to the Most Extreme.
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Ready to Watch Animal Planet The Most Extreme, Season 4, Episode 59?