One of my favorite series right now is the Warriors series, by Erin Hunter. It's basically a fantasy about cats--as in house cats, except they don't live in houses. They live in the wild.
It's not as chaotic as you might think. The cats are structured into four Clans: ThunderClan, RiverClan, ShadowClan, and WindClan. Each Clan has a leader, a deputy, and warriors.
The cycle starts with the kittens, or kits. When a kit is born, its name ends in the suffix 'kit' (example: Bluekit). When they reach six months, or moons, old, they are apprenticed to a warrior of the Clan, and the suffix is changed to 'paw' (example: Bluepaw). When they've had at least five moons of training, they become warriors, and the suffix becomes anything other than kit, paw, or star (example: Bluefur). If they become leader, the suffix is changed to 'star' (example: Bluestar).
A good friend (who shall remain nameless) and I have been trading a lot of emails on the topic of this series recently, and now we're thinking of writing down a revisionist version (or something like that). The idea is that the villain (whose name is Tigerclaw, by the way), is really the good guy, and was framed by the two protagonists, Bluestar and Fireheart (I'm doing my best not to give any important parts of the series away, in case anyone reading this should ever read the series). Once all the cats figure out that Tigerclaw wasn't the villain everyone said he was, everyone takes sides, and a huge war ensues.
I'd like to recommend to the Warriors series to anyone reading this blog who likes animal fiction. Just to warn you, the series is long, (twenty-four books) and the books are moderately long (two hundred to three hundred pages long), but other than that, it's great!