The Yungas of Jujuy: Cloud Forest, Biodiversity and Calilegua National Park

The Yungas are a strip of subtropical mountain cloud forest running along the eastern flank of the Andes from Venezuela to northwest Argentina. In Argentina they extend primarily through Jujuy, Salta and Tucumán, in an altitudinal band between 400 and 3,000 meters above sea level. They are Argentina's most biodiverse ecosystem and one of the most threatened biomes on the planet.

What makes the Yungas unique is the combination of variables: humid easterly winds from the Atlantic strike the Andean slopes and form a permanent cloud layer between 1,000 and 2,000 meters that feeds dense, extraordinarily diverse vegetation. Temperature varies radically with altitude: in the lower yungas (up to 1,000 m) the climate is subtropical humid; in the mid-yungas it is cool-temperate; in the upper yungas (above 2,000 m) it transitions to the cloud grasslands.

Visually, Jujuy's Yungas contrast radically with the aridity of the Quebrada de Humahuaca or the bareness of the Puna: here everything is green, the vegetation is dense, the air smells of damp earth and it rains frequently between October and March.

Calilegua National Park covers 76,306 hectares in the Ledesma department, about 120 km southeast of San Salvador de Jujuy. Created in 1979, it is the largest national park in the Argentine Yungas. It protects a complete altitudinal strip from 450 meters at the foothills up to 3,600 meters of high-altitude grasslands on the hills bordering the Puna.

The main access is via Provincial Route 83, which departs from the city of Libertador General San Martín (Ledesma), about 90 km south of San Salvador on National Route 34. Visitor services are at the Aguas Negras Visitor Center, next to the entrance; the road then continues to the small mountain village of Valle Grande, about 22 km away. RP 83 is a gravel mountain road with sharp bends and wildlife often crossing; to check its condition, especially after rain, ask at the Aguas Negras Visitor Center, staffed every day from 8 am to 7 pm.

The park has self-guided trails and recreation areas in the Aguas Negras and Mesada de las Colmenas sectors, plus the Aguas Negras rustic campsite, free to use, with 25 pitches, fire pits and bathrooms with hot showers (no electricity or shop). For the longer trails, ask at the Visitor Center about licensed local guides.

Calilegua's fauna is extraordinary. Among large mammals: the lowland tapir (Tapirus terrestris), the jaguar (Panthera onca) — whose presence is sparse and sightings extremely rare — the puma (Puma concolor) and the white-lipped peccary. The tapir is the easiest to spot at dusk in clearings near the river.

With over 300 recorded species, the park is a top-tier birdwatching destination. Among the most sought-after birds are the green toucan, the mountain chachalaca, several Andean parakeets and the harpy eagle (rare but present). The peak period for bird activity is September to November, during migration and the breeding season.

The flora is equally diverse: the cedro coya, the pino del cerro (Podocarpus parlatorei) and the criollo walnut dominate the mid-yungas sectors. Native orchids — over 20 species recorded in the park — bloom between October and January. Tree ferns reaching over 5 meters create environments more reminiscent of a New Zealand fern valley than northern Argentina.

From San Salvador de Jujuy the most direct route is National Route 34 south to Libertador General San Martín (90 km, approximately 1 hour 15 minutes by car), then Provincial Route 83 north to Valle Grande (22 km, another 45-60 minutes on the winding road). Total: about 2 hours from San Salvador.

Every day at 8 am a bus leaves the Libertador General San Martín terminal for San Francisco and Valle Grande, crossing the park (ask to get off at Aguas Negras) and returning in the afternoon; remises and taxis can also be hired in Libertador and Calilegua. For a comfortable visit, a private car or an organized excursion from San Salvador de Jujuy is the best option.

If you are traveling from the Quebrada de Humahuaca, the circuit can be done by taking National Route 9 south from San Salvador and combining the Quebrada north-to-south with Calilegua as the closing point before reaching the airport. Budget at least a full day for the park — a brief visit does not do justice to the scale of the ecosystem. See also: car rental guide for Jujuy.

The dry season (May to October) is recommended for visiting Calilegua National Park. The access road can become seriously compromised by the wet season rains (November to March): heavy showers can turn the dirt into impassable mud and cause landslides on steep sections.

April and May are particularly good: the park is at its greenest post-rain, temperatures are pleasant (20-25°C in the lower yungas) and wildlife is very active before the winter cold. September and October are the best months for birdwatching: the vegetation is more open and migratory birds arrive in greater numbers.

July — Jujuy's most visited month overall — is valid for Calilegua, but winter temperatures in the park's higher sectors (Valle Grande at 1,500 m) can drop considerably, and the forest is less dense, which helps spot wildlife but reduces the visual impact of the vegetation.

Always bring high-concentration insect repellent: jejenes (tiny biting gnats) and horseflies are intense in the wet season and moderate the rest of the year. Long-sleeved clothing is essential on the trails.

Entry to Calilegua National Park is free, as is the Aguas Negras campsite. The national parks agency plans to start charging at some point (the park already appears in its 2026 fee schedule, but with no charge until access control is in place), so check the official website before you go. Always register at the park headquarters before entering the trails: the park has areas with difficult access and no cell communication.

The short, marked self-guided trails in the Aguas Negras sector are accessible to travelers without technical mountain experience and offer good birdwatching; ask for the current map of open trails at the Visitor Center. For longer trails into the park's interior, going with a local guide is recommended.

Minimum equipment: trekking boots with good grip (the wet forest floor is slippery), long-sleeved clothing, insect repellent, a rain poncho (afternoon showers are frequent even in the dry season), water and food — there are no food services inside the park except in Valle Grande.

If you want the total Jujuy contrast experience, the ideal itinerary combines the Quebrada de Humahuaca and Puna with Calilegua: in less than 200 km you can go from the 3,500-meter salt flat to the 500-meter subtropical jungle — two worlds that share an administrative border but have absolutely nothing in common visually.