The National Park Headquarters at Santa Fe 680 in Buenos Aires (Mon-Fri 10am-5pm; tel 011/4311-0303) has an information office on the lower ground floor, with introductory leaflets on the nation's parks, though some are occasionally out of stock. A wider range of free leaflets is often available at each individual park, but these are of variable quality and limited funding means that many parks give you only ones with a basic map and a brief park description. Contact the headquarters well in advance if you are interested in voluntary or scientific projects. Nature enthusiasts would gain more from a visit to the Fundación Vida Silvestre than they would from a visit to the National Parks' headquarters in the capital. The Fundación, located at Defensa 251, Piso 6K, (1065) Buenos Aires (Mon-Fri 10am-1pm & 2-6pm; tel 011/4343-3778 or 4331-3631; www.vidasilvestre.org.ar ), is a committed and highly professional environmental organization, and is an associate of the World Wide Fund for Nature (WWF). Visit its shop for back issues of its beautifully produced magazine, for books and leaflets on wildlife and ecological issues; as well as for information on its nature reserves. Bird-watchers should visit the headquarters of the country's well-respected birding organization, Aves Argentinas/Asociación Ornitológica del Plata , at 25 de Mayo 749, Piso 2K "6", (1002) Buenos Aires Capital Federal (Mon-Fri 2.30-8pm; tel & fax 011/4312-1015; aop@aorpla.org.ar ). They have an excellent specialist library ($5 per day for non-members) and a shop, and they organize morning outings once a month to the capital's prolific Costanera Sur marshland reserve (on weekends; $5), and birding safaris around the country (at prices far more accessible than most specialist overseas operators. A $50 annual membership for foreigners entitles you to their high-quality quarterly magazine, discounts on bird safaris, free access to the library, and the possibility of getting involved in scientific and conservation work. Each national park has its own Intendencia , or park administration, although these are often in the principal access town, not within the park itself. An information office or visitors' centre is usually attached, and you can usually buy fishing licences here. Parks are often subdivided into more manageable units: the larger divisions of which are called seccionales , often with some sort of small information office of their own in the main building. Argentina's guardaparques , or national park rangers, are some of the most professional on the continent: generally friendly, well-trained and dedicated to jobs that are demanding and often extremely isolated. All have a good grounding in the wildlife of the region and are happy to share their knowledge with those who express an interest, although don't expect them all to be professional naturalists - some are, but ranger duties often involve more contact with the general public than with the wildlife. You may need to register with the guardaparque before heading out on treks or to seek camping permits.