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Bosque del Río Tigre
Sanctuary & Lodge
Dos Brazos, Costa Rica

The Osa Peninsula: A world treasure

The Peninsula de Osa hosts no less than 50% of the species in Costa Rica

The Peninsula de Osa, on the southwestern coast of Costa Rica, is one of the last truly remote areas in Costa Rica. To the east of the Peninsula is the beautiful and deep Golfo Dulce, one of only 4 tropical fiords in the world and the only known central Pacific calving ground of the Humpback Whales. To the west lies the Pacific Ocean and in the northern corner  is one of the largest pacific mangroves in all of Central America. Four species of sea turtle nest on the peninsula's beaches and dolphins are seen regularly  just off the shore line.

The interior of the Peninsula contains the largest lowland rainforest and the only remaining Pacific lowland rainforest in Central America. Half of this forest is represented by Corcovado National Park and the other half is in the adjoining Reserva Forestal Golfo Dulce. The Reserva is the equivalent of a National Forest.

The Peninsula is considered one of the most bio-diverse places on earth. Due to its unusual, early geographic history, the Osa hosts an astounding number of endemic species (species found no where else in the world)

…..and a disturbing number of species that have been classified as "endangered or threatened"!

The Species of the Osa

  • 375 species of birds of which 1 species is endemic and 40 are endangered or threatened within Costa Rica…( we have now (unofficially) counted over 400 species)
  • 3100 species of plants, 67 of which are endemic to the Osa and 57 species recently reported as new to science.
  • Of these plant species, 750 species are trees and 23 are endangered or threatened.
  • Of the 124 species of mammals and 13 are in danger of extinction.
  • 6000 species of insects,
  • 117 species of amphibians and reptiles.  14 species reported with threatened populations and 6 are endangered, including 4 species of sea turtle.
  • 40 species of freshwater fish of which 9 are endemic to the Osa…

Note:  Some of these figures are approximate.  There are many species as of yet undiscovered or unstudied and species counts vary slightly from source to source
Figures from "Area Biodiversidad del Area de Conservation Osa" Opinion Ambiental, Oct 2001 by Randall Garcia, INBIO, "Costa Rica Natural History" edited by Daniel Janzen 1983,  "Especies de Flora y Fauna Silvestre con Poblacions Reducidas y en Peligro de Extinción", 1998 Juan Rodríguez Ramírez and Jorge Hernández Benavides),  Introductory Field Guide to the Flowering Plants of the Golfo Dulce Rain Forests, Costa Rica, 2002, Regenwald Der Osterreicher.

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