Hi All
I didn't respond the first time around as I figured there would be lots of
bites at this topic. Anyway, for owls, I would highly recommend North
American Owls, Biology and Natural History by Paul A. Johnsgard, 1988. Part
one of the book deals with the comparative biology of owls as a general
topic. The second 2/3's covers each NA species. Each species discussion
covers range, subspecies, measurements, weights, description,
identification, vocalizations, habitats & ecology, movements, foods &
foraging behavior, social behavior, breeding biology, and evolutionary
relationships and conservation status.

Of course the bible on gulls is Gulls, A Guide to Identification by PJGrant,
1986 (paperback 1997). What else can you say. It's the one to have, and I
wish it had a ton more illustrations.

Cheers
Gail Spitler
Johnsons Landing, BC
spitler at wkpowerlink.com