Friends, old and new?

I hate deserting an old friend, a companion that has stood faithfully by through many adventures for nearly fifteen years, but alas, both my geography and experience necessitate it.  So I bid a fond farewell to Peterson's 'Guide to Eastern Birds.'  But like many an old book, I can return to it at leisure or need and renew our acquaintance though I have found younger and more relevant friends to accompany me into the field.  Yes, I fear birdwatching is even more an obsession for me than writing this time of year.