Marismas Nacionales is a vast complex of mangroves, saltwater lagoons, lakes, and plains with flood defences situated on the northern Pacific coast. The mangroves cover 113,000 hectares, accounting for more than 20 per cent of the country’s total mangrove area. Rivers and seasonal streams flowing from the Sierra Madre Occidental Mountain range have created fertile valleys in which the local population is concentrated. The Site’s important fish populations and its tropical tree species provide food and materials for building and roofing to the local communities. There are 73 nationally threatened species within the Site. These include the lilac-crowned Amazon parrot (Amazona finschi) and the rooster hind (Hyporthodus acanthistius). The Site is affected by a reduction in freshwater flows due to road construction and the retention of sediment by nearby dams.