Checklist of Costa Rican Birds:

Official Checklist of Costa Rican Birds in excel http://avesdecostarica.org/ListaOficial2007.xls

List of Birds of Costa Rica from Wikipedia http://en.wikipedia.org/wiki/List_of_birds_of_Costa_Rica

Bird Field Guides:

A Guide to the Birds of Costa Rica    by F. Gary Stiles & Alexander F. Skutch
http://www.abasales.com/index.php?main_page=pubs_product_book_info&products_id=301

Birds of Costa Rica: A Field Guide    by Richard Garrigues
http://www.abasales.com/index.php?main_page=pubs_product_book_info&cPath=19_22_41&products_id=1946

A Guide to the Birds of Panama with Costa Rica, Nicaragua, and Honduras, 2nd Edition   by Robert S. Ridgely & John A. Gwynne, Jr.
http://www.abasales.com/index.php?main_page=pubs_product_book_info&products_id=21

Audio Field Guides:

http://www.tinkfrog.com/

Tourist Map
http://www.visitcostarica.com/ict/paginas/mapas/MAPA_TCR_COSTARICA_ICT.jpg

General Nature, Flora, Fauna: