The Tribes of Redwall: Otters

Written by Brian Jacques
Illustrated by Jonathan Walker

The Tribes of Redwall is a companion series to Redwall. The Tribes of Redwall: Otters is the second book in the series (the first being Badgers). The companion (similar to the Redwall Riddler and Friend & Foe) will contain information on the main otter characters, a quiz, and a poster.

Another blurb about the Tribes series:

This series takes a closer look at the clans and tribes who defend the Redwall Abbey from the threat of evil throughout Mossflower and beyond.