If you are SERIOUS about your owl pellets, this is much more than an excellent dichotomous key. The 162 page key includes outstanding skull illustrations, range maps, species descriptions and life histories. A map and description of the primary vegetation types in this region as well as a glossary of terms and extensive literature sited. If you REALLY want to know what is in your owl pellet this is a wonderful resource for your classroom. You will never think, "a mouse is a mouse" again! Ages 15 and above.