I work at a rehabilitation center (Liberty Wildlife) that has been helping save Arizona's native wildlife for 27 years and receive over 4000 native animals yearly (most or which are birds), so we have a large wealth of knowledge there. This book gave us that extra edge in helping us to rehabilitate the more difficult and lesser seen orphaned birds as well as the common ones! It goes through everything from hatchlings to nestlings to fledglings and describes how the dietary needs of the birds change and at what stages to do that. This is especially helpful with finicky birds such as the corvids where it maps out a daily regiment to feed these birds. It also covers a very wide variety of species, from US natives to lots of different exotics as well as common diseases that can afflict the various species and what to look for/how to cure it. I found this especially helpful in the finch section that describes "sudden finch death syndrome" which we see often at the facility and now have new tools to combat it. I've never found a book on the subject that's even close to as informative as this. This is a MUST HAVE book for anyone hand-rearing birds. Even those who think they know it all will probably get some new and useful ideas from this book.