I've just finished something of a tutorial to teach people (including myself) about the exact causes for animal jumping; animals being sheep, skunks, moles, cows, old ladies, and salvation armies. It's pretty in-depth, and if there's one thing you should remember from it, it's definitely the height of that ceiling in the Narrow Area Behavior section.
http://worms2d.info/Animal_JumpingReading this will save people serious pain when it comes to animals. You'll be able to more clearly see beforehand what kind of routes are possible/impossible for an animal to take, and where the animal is most likely to go. There is also an amazing replay at the end, brought to you by Deadcode.
I'm extremely grateful to Deadcode, who helped me get many of the facts right that I couldn't possibly observe just through testing, and Cybershadow helped me a bit earlier on too. There may still be some minor inaccuracies, but I'll mention when anything changes.
