Tails are extremely useful to mice, especially for balance and climbing: https://www.theguardian.com/lifeandstyle/2019/apr/30/why--mice-such-long-tails-notes-an

Tails are extremely useful to mice, especially for balance and climbing: https://www.theguardian.com/lifeandstyle/2019/apr/30/why--mice-such-long-tails-notes-and-queries#comment-128531286 https://www.theguardian.com/lifeandstyle/2019/apr/30/why--mi... Be careful with assuming functionlessness, in general. Evolution does not like spending energy on sticky-out bits that are prone to injury, or good handles for predators to catch, unless they provide some serious advantage.