The Amazing Osa Peninsula
Costa Rica, located between Nicaragua and Panama, is one of the seven Central American countries and covers an area of 51,100 km2. It is surrounded by the Pacific on the west and the Caribbean on the east, creating a coast line of 1103 km and 255 km respectively. Even though this small country covers only 0.03 percent of the earth’s surface, it contains almost 5% of the world’s biodiversity, including around 12,000 plant species, 1,600 butterfly species, 838 bird species, 440 reptile and amphibian species, and 232 mammal species. The high species richness has been attributed to two main factors: its geographical location and climatic conditions. Another factor that makes Costa Rica special is that it is situated between North and South America, meaning it can serve as a species corridor between these two continents, thus allowing for migration and exchange of genetic diversity.
Costa Rica lies halfway between the Tropic of Cancer and the equator, leading to an annual average temperature of 27 °C, with very little fluctuations throughout the year. Therefore, the seasons in this area are defined by precipitation, not temperature, resulting in a distinct dry and wet season. The dry season starts around November/December and continues through April/May, after which the rainy season begins. The Southern Pacific Lowlands, where the Osa Peninsula is located, receive a particularly high degree of average annual rainfall (about 7,300 mm).
Although more than one-fifth of Costa Rica is protected, the protected areas are becoming increasingly isolated, raising questions about the ecological functionality of the protected areas network on a regional and national level. In the absence of connectivity, the structure, dynamics and diversity of the forest flora changes and the ability for these fragmented areas to sustain both genetic and species diversity is reduced; especially in the face of extreme climatic events and disturbance. The World Resource Institute states that further action must be taken in order to raise, or at least sustain the current level of biodiversity (World Resources Institute, 2006). The main threat to the ecosystems in Costa Rica, and the reason for the reduction and fragmentation of forests, is land use and land cover change, which is driving biodiversity loss globally as the human population continues to expand. Other issues include pollution, climate change and invasive species.
The Osa Peninsula
The Osa Peninsula is located in the Southwest of Costa Rica and covers an area of 1093 km². The peninsula contains the last remnants of tropical broadleaved evergreen lowland rainforest on the Central American Pacific Slope and holds a very high species richness, containing around 50% of Costa Rica’s biodiversity in just 5% of its land mass. Furthermore, this area is home to several endemic species, such as the Cherrie’s tanager (Ramphocelus costaricensis), the red-backed squirrel monkey, or titi monkey as its better known in Costa Rica (Saimiri oerstedii) and the Golfo Dulce poison dart frog (Phyllobates vittatus). Since these and more species are only found in this area, it makes the Osa Peninsula the ideal location for conservation research.
Three main forest types can be found in the Osa Peninsula; Tropical Wet, Premontane Wet and Tropical Moist forest, with elevations ranging between 200 and 760 m. The variation in topography leads to a highly variable climate, with an average annual rainfall of 5500 mm, a mean temperature of around 27 °C and humidity levels almost never dropping below 90%. There are around 12,000 people living in the Osa Peninsula, mainly settled in small and scattered villages. The most important sources of income in this region are agriculture (rice, bananas, beans and corn), livestock (cattle), gold mining, logging and, more recently, the expanding eco-tourism industry. On the Osa, the human population is increasing at a rate of 2.6% annually, which is incredibly high compared to 1.3% in the rest of the country and 1.14% globally. As a result of the growing popularity of ecotourism, there has been a rise in the number of hospitality business along the road from Puerto Jimenez to Carate since the 1990's. This, combined with meeting the demand for the growing population in the area and high rates of agriculture, has caused growing concern for the sustainability of the regions environmental resource demands and protection of its ecosystems.
Nationally, the priority for the Osa Peninsula is reconnecting the land between the national parks in the area: Corcovado, Piedras Blancas, Terrebe-Sierpe and the La Amistad National park in the Cordillera de Talmanca. The region is one of the most heavily affected areas in the country in terms of the fragmentation of land. These protected areas currently exist within a network of agricultural land and unprotected forests, reducing the ability to support wildlife. Wildlife cannot exist in a box and needs room to move, especially in the face of climate change. Restoring and reconnecting habitats is essential if we are to protect wildlife from further losses.
Fascinating Osa Facts
1. 50% of all Costa Rican species are in the Osa- Making the Osa the most biodiverse place in the world. The Osa covers only 5% of the land mass of Costa Rica, around 1000km 2 compared to the almost 20,000 that Costa Rica covers.
2. The Osa has the last remaining lowland rainforest along the Pacific coast of Central America. This is important as Caribbean rainforests and even Pacific rainforests in South America hold a very different biodiversity.
3. The Osa holds many endemic species due to the joining of two land masses 2 million years ago. Many animals never made it across the Talamanca mountain range so are limited to the Osa. 10% of flora (plants) are found nowhere else in the world and 25% of amphibians are endemic.
4. The Osa is a migratory route and seasonal feeding ground for many species of bird from the United States and Canada.
5. The Osa has a wide variety of habitats/micro climates, supporting some of the worlds most threatened ecosystems including mangrove forests and wetlands. It holds the most significant wetland ecosystem and mangrove forests of Central America.
6. The Osa has the largest population of Scarlet macaws in Central America and one of the only remaining populations in Central America.
7. The Osa boasts more than 700 species of tree (which is more than all the Northern temperate regions combined!!!)
8. The Osa has 234.8 plant species per 1 000 km2, Colombia, the 2nd most biodiverse has only 43.8 plant species per 1 000 km2.
9. The Osa holds 28.2 species of vertebrates (excluding fish) per 1 000 km2, Ecuador, the 2nd most biodiverse has 9.2 species per 1 000 km2, and the third most biodiverse vertebrate country, Malaysia, has only 4.4 vertebrate species per 1 000 km2.
10. The Osa has 463 species of birds, one of the highest densities in the world.
11. There are 140 species of mammal, including 25 species of dolphins and whales.
12. There are 4 species of sea turtles that nest on the beaches on the Osa.