Laguna Oca is an amazing birding location. Over 350 species in one park just outside the city. The state of Formosa has over 500 species. I visited the island in the center of Laguna Oca for just one hour midday, and must have seen 30 to 40 species. And the park has a large number of 'eco policia' making it a secure place for photography. Read my trip report North Argentina March 2008 for more information.
Africa (entire continent rather than south of Sahara)
AN
Antarctica
AO
Atlantic Ocean
AU
Australasia (Wallacea (Indonesian islands east of Wallace's line), New Guinea and its islands, Australia, New Zealand and its subantarctic islands, the Solomons, New Caledonia, and Vanuatu)
PAL
Eurasia (Europe, Asia from the Middle East through central Asia north of the Himalayas, Siberia and northern China to Japan)
IO
Indian Ocean
LA
Latin America (Middle and South America)
MA
Middle America (Mexico through Panama)
NA
North America (includes the Caribbean)
NO
Northern oceans
OR
Oriental Region (South Asia from Pakistan to Taiwan, plus Southeast Asia, the Philippines, and Greater Sundas)