• Spider Monkey (credit Andrew Whitworth)

    Costa Rica: Preventing Ecosystem Collapse in the Osa Peninsula and beyond

  • Lachesis melanocephala (credit Andrew Whitworth)

    Costa Rica: Preventing Ecosystem Collapse in the Osa Peninsula and beyond

  • photo: Carlos R. Garcia

    Costa Rica: Preventing Ecosystem Collapse in the Osa Peninsula and beyond

  • photo: Charlie Hamilton James

    Costa Rica: Preventing Ecosystem Collapse in the Osa Peninsula and beyond

  • photo: Carlos R. Garcia

    Costa Rica: Preventing Ecosystem Collapse in the Osa Peninsula and beyond

  • photo: Carlos R. Garcia

    Costa Rica: Preventing Ecosystem Collapse in the Osa Peninsula and beyond

In Brief

Conservation Value:

The Osa Peninsula contains the largest mesic rainforest remaining on the Pacific slope of Central America, largely within Corcovado National Park. It has the largest expanse of mangrove wetlands on the Pacific slope of Central America and a unique coastal marine ecosystem—the Golfo Dulce tropical fjord.  The Osa is estimated to house 2.5% of the world’s biodiversity while covering less than 0.001% of its total surface area, and was described by National Geographic in 2016 as “the most biological intense place on earth”.


The main threat in the Osa Peninsula is illegal hunting, which is still prevalent in the region.  The concern is greatest with respect to the lowland paca (Cuniculus paca), white-lipped peccary (Tayassu pecari) and collared peccary (Pecari tajacu). Other species are hunted to a lesser degree, including game birds such as: tinamou (Tinamus major and Tinamus major castaneiceps) and great curassow (Crax rubra).  Research has identified key areas of hunting pressure, however no concerted effort had been been made to reduce illegal hunting on the peninsula. A presentation at the 21st Mesoamerican Congress in San Jose in 2017 revealed that bushmeat offtake could be around 28.5 kg per year for each family hunting in the peninsula.

Actions & Results:

Osa Conservation (OC) is leading a conservation effort that mobilizes citizen scientists, community members, ecotourism operators, park administrators and multiple NGOs to preserve the globally significant biodiversity of the Osa Peninsula in the face of climate change. To accomplish this, connectivity must be re-established from the Osa lowland rainforests to the Talamanca Mountains. In collaboration with a network of partners and local stakeholders, OC is rebuilding this connectivity via its 'Ridge to Reef' initiative to help protect one of the world’s last wild places. In 2022 OC planted 40,000 mangrove trees to restore 40 ha of degraded mangrove forest in the Térraba Sierpe wetlands—the largest protected wetland in Central America. It also planted 81,062 rare, native, and threatened trees species, to connect landscapes so biodiversity can thrive. OC trained 30 volunteer rangers to patrol 69,731 km of forest which generated 27,265 field biodiversity observations. This data was integrated in real time into the first Earth Ranger project in Latin America. It also protected and released 28,272 sea turtle hatchlings—for a total of 208,700 hatchlings released by OC—and collected 1,135 lbs. of garbage from pristine sea turtle nesting beaches with the help of 215 volunteers. To build capacity at the local level and to empower civil responsibility, OC employed 114 local community members through restoration, research, and conservation initiatives, and hosted over 400 community members at the bi-annual Rainforest Heroes Celebration. After its successful inaugural year (2021), OC's 'Ridge to Reef Nature Club' continued to provide rural youth with an immersive nature-based learning model and to raise the next generation of conservation stewards. The Club grew to 9 chapters and engaged 2,521 youth across the Osa region in 2022.

Zero in on one community involved in this project in this short video from the Our Planet series.

See more videos below.


Osa Peninsula, southwest Costa Rica


To increase ecosystem resilience by restoring apex predator and prey populations and habitat connectivity in the Osa Peninsula

Project Field Partner:

Osa Conservation


Ridge to Reef program
Cumulative cost to ICFC (2018-2022): CA$798,498

Osa Youth Nature Program
Cumulative cost (2021-2022:) C$124,776

Size of Area Involved:

109,300 hectares (1,093 km²)


Support this project


Click to enlarge an image

6. white-lipped peccary (tayassu pecari) wallow fun (credit osa conservation) copy
4. a juvenile ocelot caught on camera trap in piedras blancas national park, found moving up the highest ridge line. photo credit amistosa camera trap network (2020) copy
Jaguar octn copy
85. osa peninsula trip 2020 copy

In More Depth...

Videos: Rainforest Heroes of the Osa

         Osa SAFER – Rainforest Heroes of the Osa Peninsula: Tomas Ridings Muñoz

         Osa SAFER – Rainforest Heroes of the Osa Peninsula: Marvin López Morales

Highlights from 2018 to 2020

• Twelve forest acoustic monitoring devices were deployed in 2018. Three of these are streaming live and you can get the Rainforest Connection App on iOS or Android to listen to the calming noises of the rainforest at Osa Verde Biological Station, Golfo Dulce Forest Reserve, and Corcovado National Park. In addition, 25,000 native forest trees and over 13,600 mangrove trees (of four species) were planted, and 280 bird boxes were also installed in 2018.

• Monitoring and enforcement activities conducted in 2018, in collaboration with local Community Biological Monitoring Groups, the Department of Protection and Control of the Ministry of Environment and Energy of Costa Rica (MINAE), and Special Police Units, resulted in two police operatives around Corcovado National Park that led to the arrests of several people carrying out illegal gold mining and hunting activities in the region.

• Thanks to the expansion of the Osa Camera Trap Network (OCTN), major strides were made in 2019 in deterring illegal human activities and augmenting the ability of government officials and private landowners to respond to illegal incursions. The OCTN monitors 8,650 hectares that border protected areas – land that is owned by OC, eco-lodges and private finca owners.

• OC’s rapid-response rangers (COVIRENAS) completed 1,649 km of patrols in 2019, leading to the arrest of 13 illegal gold miners within Corcovado National Park.

• OC planted over 20,000 mangrove trees and initiated wildlife monitoring in its program to kick-start regeneration in degraded forest patches.

• Over 2,000 participants received tropical rewilding education through a wide variety of experiential activities and workshops, and OC provided citizen science and conservation technology training to four local biological monitoring groups in forest dependent communities. All of this is bringing a noticeable cultural transformation towards conservation in the Osa Peninsula.

• OC launched its Ridge to Reef Program, expanding its camera trap network across the newly designated AmistOsa Biological Corridor in 2020. The plan is to monitor biodiversity and work with local communities to conserve and restore the biological corridor connecting the highland forests of the Talamanca Mountains to the lowland forests on the Osa Peninsula. Phase 1 involved deploying 234 camera traps, 41 acoustic devices and 41 temperature loggers (iButtons) along a 190 km transect (ranging in elevation from sea level to 2,900 m).

• In 2020, the Osa Restoration & Rewilding Community Network planted over 18,000 trees, bringing its total to 350,000 trees planted in the past seven years.

• Although schools were closed due to the pandemic (2020), students and community members took part in outdoor small group activities and over 20,000 students were reached through virtual education events.

• OC’s rapid-response rangers (COVIRENAS) completed 2,020 km of patrols in 2020 and received drone pilot training.

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