The lakes in the northern part of the reserve are fed by the Colorado River. The very humid tropical forest is influenced by excessive humidity, rapid drainage, and thin soils, with over 330 days of cloud cover per year. Moisture-laden winds come from the Caribbean. The park has worked with the neighboring village of Tortuguero to help its inhabitants understand that preserving their natural resources is the key to encourage eco-tourism. With rich water resources from precipitation of per year, the drainage system of the park is fed by many rivers. There are a large number of interlinked canals, waterways, navigable lagoons, and lakes that create plains of sediment carried by the river system. The plains are interspersed with rolling hills of forest that were created in ancient days from volcanic cinder cones, of which the Tortuguero Hill and the Lomas de Sierpe of height could be mentioned. Enforcement of protection has remained a challenge. Swaths of the park have been semi-legally clear-cut, the damage which allows access to habitat of endangered sea turtles. Fauna and flora The national park's wild life consists of birds, mammals, fungi, ferns, marine life, sea turtles, lakes and rainforest. Tortuguero National Park acts as a refuge to many of these species which are also found in the La Selva Biological Station and Braulio Carrillo National Park. Threatened animals species in the reserve area are: the American crocodile (Crocodylus acutus), Baird's tapir (Tapirus bairdii), marine turtles such as Chelonia mydas and Dermochelys coriacea, the manatee or sea cow (Trichechus manatus) (the northeastern Caribbean wetland is its local feeding and reproduction area) and the tropical gar (Atractosteus tropicus) a living fossil brought under protection by Costa Rican legislation. The park is a breeding ground along the Caribbean coast of Costa Rica for many of the main fishes used in subsistence fishing. Fauna The coastal zone, which has a long beach extending to nearly , is the nesting ground for turtles popularly known as the "beach-nesting turtles (tortugas)". They are found on the beaches, and also many of these species are reported from the canal banks. The main species to lay eggs during the winter months of February to July are: hawksbill, loggerheads, green, and leatherbacks. The rivers are home to sensitive populations of manatees, as well as caimans, crocodiles, and tropical gar. The forests are home to at least four Costa Rican cat species: jaguars (Panthera