I actually doubt I have anything in my arsenal at the moment but have you tried the Eyewitness Childrens Books published by Dorling Kindersley? They have some of the greatest photo refs in the world and they also produce sticker sets based on themes like Birds, Sea life, etc. There's sure to be something there for you. If I can remember, I'll try to look through my books at work, I'm sure there's at least one on otters, sea lions, and the like. :)