El Rey

El Rey National Park is located in the Yungas foothills of Salta Province, northwestern Argentina, covering approximately 44,162 hectares. ^[1] The park protects a remarkable transition between the high Andean yungas (subtropical mountain forests) and the lowland Chaco plain, creating an extraordinary concentration of biodiversity within a relatively small area. Founded in 1948, it is the first national park established in an Argentine province. ^[2] The park encompasses rugged mountain terrain with peaks reaching 2,200 meters and descends to lowland forest at around 700 meters. Its isolation and relatively intact forest make it an important refuge for species that have been depleted across much of northwestern Argentina.

El Rey supports extraordinary biodiversity thanks to its position at the confluence of Andean and Chaco ecosystems. Jaguars (Panthera onca) are present but rare. Tapirs (Tapirus terrestris)—the largest terrestrial mammal in South America—inhabit the dense forest interior and are emblematic of the park. Pumas, ocelots, and jaguarundis complete the cat guild. Giant anteaters, giant armadillos, marsh deer, and brocket deer are all recorded. The park hosts 44 mammal species in total. ^[1] The avifauna includes red-legged seriemas (chuñas de patas rojas), chachalacas, mountain guans, toucans, and numerous tanagers typical of the Yungas ecoregion. The park is recognized as an important bird conservation area.

The park's vegetation is structured in distinct altitudinal zones. The lower slopes (700–900 m) support yungas piedmont forests with dense, humid understory, dominated by tipa (Tipuana tipu), nogal criollo (Juglans australis), and palo blanco (Calycophyllum multiflorum). ^[1] At mid-elevations (900–1,500 m), montane forests feature massive Myrtaceae trees and abundant tree ferns, epiphytic orchids, and bromeliads. Upper cloud forests (1,500–2,200 m) are characterized by alder (Alnus acuminata) and myrtles. One plant species—Aphelandra lilacina—is endemic only to El Rey. ^[2] The transition zone at the park's eastern boundary shows the abrupt shift to Chaco dry forest with quebracho and cactus.

El Rey sits on the sub-Andean ranges (Sierras Subandinas), a series of fold-and-thrust mountain chains that form the eastern margin of the Andes in northwestern Argentina. The mountains expose Paleozoic and Mesozoic sedimentary rocks—sandstones, shales, and limestones—that were folded and faulted during the Miocene and Pliocene Andean orogeny. The Serranías de la Cresta de Gallo encircle the park's interior in a dramatic amphitheater formation. ^[1] The park's topography is characterized by steep-sided ridges and valleys carved by rivers draining eastward into the Chaco lowlands. Ongoing tectonic activity means the region experiences occasional earthquakes.

El Rey experiences a subtropical mountain climate with a pronounced wet season from October to April, when moist air from the Atlantic penetrates the Andes foothills. Annual rainfall reaches approximately 2,000 mm on moisture-exposed slopes, with mean temperatures of 22–25°C. ^[1] Cloud forest zones experience persistent fog and mist during much of the year. The dry season (May–September) brings cooler, clearer conditions. Summer temperatures in the lower forest reach 30–35°C while high-elevation areas remain cool. Seasonal heavy rains (December–March) can make the access road via Provincial Route 20 impassable.

The yungas foothills of Salta have been inhabited for thousands of years. Pre-Columbian cultures, including early ancestors of the Calchaquí people and later influences from the Inca Empire, used the mountain valleys for agriculture and the forests for hunting. The Inca road system (Qhapaq Ñan) passed through nearby valleys. Spanish colonizers established the city of Salta (founded 1582) as a regional center, and the nearby lowlands were converted to sugarcane agriculture during the colonial and early republican periods. The park area itself remained largely inaccessible and undeveloped due to its steep terrain, which inadvertently preserved its forests.

El Rey National Park was created on June 24, 1948, by Decree 18,800/1948 under President Juan Domingo Perón's administration, making it the first national park established in an Argentine province. ^[1] At its creation, the park encompassed fiscal land in the yungas foothills of Salta that had not been significantly exploited for timber or agriculture. The park's name comes from El Rey (The King), referring to a local hacienda whose owner, Colonel Juan Adrián Cornejo, received these lands from the Spanish Crown in recognition of his services to the King. ^[2] Over the decades, the park has been the subject of scientific research on Andean biodiversity and has contributed significantly to Argentina's understanding of the Yungas ecosystem. Management challenges include controlling invasive exotic species and addressing encroachment from surrounding agricultural areas.

El Rey offers hiking trails through cloud forest, dry forest, and open valley habitats. The Valle de los Pájaros (Valley of the Birds) trail is particularly renowned for birding, providing access to dense forest with abundant wildlife. The park's interior valleys contain natural meadows (abras) with excellent visibility for large mammals. A campsite serves as a base for exploring the park's trails and its dramatic amphitheater landscape created by the Serranías de la Cresta de Gallo. Guided tours with park rangers offer the best chances of encountering elusive wildlife such as tapirs and larger cat species. Night walks in the lower forest reveal a wealth of nocturnal insects, amphibians, and small mammals.

El Rey is located approximately 203 km east of Salta city via Route 20. ^[1] The road to the park passes through the yungas foothills and requires a 4WD vehicle for the final section. The park has a visitor center and ranger station at the main entrance. A campground is available within the park for overnight stays. Guided ranger-led tours can be arranged at the visitor center. Salta city, served by an international airport, is the most convenient base for visitors. The best visiting period is May to September when roads are more accessible and wildlife activity during the dry season concentrates animals near water. Birding is excellent year-round.

El Rey's conservation significance lies in its protection of a near-intact yungas ecosystem at a scale sufficient to support wide-ranging species such as jaguars, tapirs, and pumas. The park's isolation and mountainous terrain have helped preserve its forests, but surrounding areas face deforestation for agriculture—particularly sugarcane and soybean production in the lowlands. Invasive exotic grasses threaten forest regeneration in disturbed areas. The park collaborates with research institutions to monitor biodiversity and contributes data to regional conservation planning for the Yungas ecoregion. ^[1] Education programs target local communities and the growing ecotourism sector in Salta Province.