The Palo Verde National Park on the banks of the Rio Tempisque is one of the best wildlife and bird-watching spots in Costa Rica.

Birds of Palo Verde

The remote wetland sanctuary harbours one of Central Americas largest concentration of aquatic birds and is the most important migratory bird site of the Mesoamerican Pacific.
Hemmed in by limestone hills and rivers, the lowlands of the Tempisque basin become a vast area of wetlands in rainy season. Towards the end of the rainy season Palo Verde is home to at least 250,000 birds.
For birdwatching however dry season (Jan - April) is the best time to visit the reserve because waters largely subside and the park's many birds cluster by the remaining marshes and waterholes. Observing the fauna is particularly good because in dry season there is little vegetation to obstruct views of the roosting birds.
The Tropical Dry Forest and WildlifePalo Verde is also important for protecting one of the last significant remnants of the deciduous dry forests of the Neotropics.

 
Dry forest in Palo Verde

This sensible eco-system once covered most of Central American Pacific side but has been destroyed by man over the centuries.
With little or no precipitation for half the year, most bushes and trees in the dry forest shed their leaves to conserve water. At the peak of dry season however, many trees burst into a riot of colors with bright yellow and red flowers on bare branches.
Palo Verde forms part of the Tempisque Conservation Area which includes the Barra Honda National Park, the Caballero Wildlife Refuge, the Lomas Barbudal Biological Reserve and other patches of biological interest. The total of protected areas in the Tempisque river basin encompasses 73,000 hectares and presents 15 different habitats thus being one of Costa Rica's most biological diverse sites.
Around 75 species of mammals, including peccaries, armadillos, deer, monkeys, and coatis roam the thickets. Palo Verde harbours Costa Rica's largest population of jaguarundis, a brownish, small wild cat (see wildcats in the Wildlife Guide). 55 species of reptiles and amphibians are found, and the Tempisque river has the largest concentration of crocodiles in Costa Rica.
The abundance of flowers and fruit in the national park also feed myriads of insects and colonies of bats. Especially the Lomas Barbudal Biological Reserve, adjacent to Palo Verde, is a heaven for insectologist's: 250 species of bees have been counted which is around a quarter of the world's bee species. An abundance of wasps, butterflies, moths and other insects inhabit the forest, and in - in rainy season - there are swarms of mosquitoes.

Taken from www.nicoyapeninsula.com