Your hobby is
birdwatching (hinted by the word "hobby" and the reference to "keeping an eye on things").
The Four Feathers
What is the name of this book? (published by Pelican)
Poems of Matthew Arnold -- "Arnold" means something like "strength of the eagle", etymologically.
The Annotated Snark edited by Martin Gardner
The Testament of Mary by Colm Tóibín -- "Colm" means "dove".
I have Landed by Stephen Jay Gould
Life ... by Robin Skynner and John Cleese
Lore & Language ... -- "lore", among several other meanings, means a particular portion of a bird's head
Life and Times of the Thunderbolt Kid by Bill Bryson
Explanations that I proposed, apparently aren't the intended ones, but seem worth recording:
Matthew Arnold: one poem is called Philomena (= nightingale), and the introduction in that edition is by Sir Arthur Quiller-Couch (quiller = not-fully-fledged young bird).
Testament of Mary: I wondered whether it was the Penguin edition of that play.
Lore and language...: Opie (pie = magpie, near enough), Peter (first name of one of the two Opies who wrote the book; it denotes the call of certain birds), and Iona (first name of other author), the famous island sharing whose name is strongly associated with St Columba (meaning dove).