Here are a few must-have books for serious bird enthusiasts.

Anything by David Allen Sibley is worthwhile. His field guides are current and are considered by many as the de facto standard field guide for the birds of North America.

• The Sibley Guide to Birds
• The Sibley Field Guide to Birds of Western North America
• The Sibley Field Guide to Birds of Eastern North America
• Sibley's Birding Basics (basic)
• Sibley Guide to Bird Life and Behaviour (advanced/scientifc)

Another excellent field guide is

National Geographic Field Guide to the Birds of North America

For Argentina and Uruguay, the only book to consider is "Guia para la identification de las Aves de Argentina and Uruguay" by Narosky. However this book is hard to find in the United States, and is written in Spanish (with English bird names given). You can buy this book in Buenos Aires, but be careful because I have seen it close to $100 US. The local equivalent of the Audubon Society (I will try and find the exact name) sells it for around $30 US (95 pesos) and is where I got my copy.

For Costa Rica, the only book to consider is The Birds of Costa Rica by Richard Garrigues

For Venezula, I recommend Birds of Venezuela, by Steven Hilty, which is a large, heavily researched and detailed book. "Aves de Venezuela" appears to be out of print (and is now a collectors item). I haven't seen A Guide to to the Birds of Colombia, co-authored by Hilty, for Colombia, but if it is anything at like his book for Venezuela, it is excellent.

If you have some money to spend... The Handbook of the Birds of the World (HBW) is a multi-volume series produced by the Spanish publishing house Lynx Edicions, and is the first handbook to cover every living species of bird. Each volume lists for around $250.00, although occasionally you can find cheaper used copies on Amazon (check link below).

• Handbook of the Birds of the World, Volume 1: Ostrich to Ducks.
• Handbook of the Birds of the World, Volume 2: New World Vultures to Guineafowl.
• Handbook of the Birds of the World, Volume 3: Hoatzin to Auks.
• Handbook of the Birds of the World, Volume 4: Sandgrouse to Cuckoos.
• Handbook of the Birds of the World, Volume 5: Barn Owls to Hummingbirds.
• Handbook of the Birds of the World, Volume 6: Mousebirds to Hornbills.
• Handbook of the Birds of the World, Volume 7: Jacamars to Woodpeckers.
• Handbook of the Birds of the World, Volume 8: Broadbills to Tapaculos.
• Handbook of the Birds of the World, Volume 9: Cotingas to Pipits and Wagtails.
• Handbook of the Birds of the World, Volume 10: Cuckoo-shrikes to Thrushes.
• Handbook of the Birds of the World, Volume 11: Old World Flycatchers to Old World Warblers.
• Handbook of the Birds of the World, Volume 12: Picathartes to Tits and Chickadees.
• Handbook of the Birds of the World, Volume 13: Penduline-tits to Shrikes.
• Handbook of the Birds of the World, Volume 14: Bushshrikes to Old World Sparrows. (due 2009)
• Handbook of the Birds of the World, Volume 15: Weavers to New World Warblers. (due 2010)
• Handbook of the Birds of the World, Volume 16: Tanagers to New World Blackbirds. (due 2011)

Some beautiful gift or coffee table books include

• Firefly Encyclopedia of Birds (photos and illustrations, 607 pages)
• Bird - The Definitive Visual Guide by Birdlife International (a great organization) (photos and illustrations, 512 pages)
• Hummingbirds of Costa Rica (pretty photos)