Over 520 species have been recorded in this area, with at least 150 migratory species that use the terrestrial and the marine coastal habitats while migrating. This region is characterized by the presence of several types of swampy wetlands and lakes, natural forest, secondary forest, and agricultural livestock. On this region there are important National Parks and conservation. The temperature is typically hot and humid; receive an average rainfall between 2,600 to 6000 mm throughout the year, with the wettest months being July and December. Statistically there are two somewhat drier periods, one during March and April and another in September and October; however it can rain any time of the year. One of the most important bird in these region in terms of conservation is the Great Green Macaw (Ara ambiguus) it is a estimated population of shared between Nicaragua and Costa Rica is less than 90 individuals. It is the place to find species like Snowy Cotinga, Plain colored Tanager, Nicaraguan Seed-finch, and Nicaraguan Grackle, Black-crowned Antshrike, Chesnut colored woodpecker.
Northern Pacific Lowlands
Most of the forest in this zone is typical of the Meso-American Dry Forest, rainfall is markedly seasonal, with a rainy season from May to November and a dry season from December to April. This region is the driest in the country because the air currents pushed along by the northeast trade winds have lost most of their moisture by the time they cross the Continental divide. The seasonality greatly influences the bird species, since there are high and low seasons of resource availability. The dry climate continues up the Pacific side of Central America and into Mexico. Species like Lesser Ground-Cuckoo, Pacific Screech Owl, Elegant Trogon, Turquoise-browed Motmot and White throated Magpie Jay, Double-striped thick-nee, Crested Bobwhite can be found here. Several neotropical migrant species are particularly abundant in this zone, such as the Scissor-tailed Flycatcher, Western kingbird, and Western Tanager. Along the coast, there are several migratory Shorebirds that reproduce in boreal areas of North America.
Southern Pacific Lowlands
This area covers maily montane areas along the four mountain ranges, the topography is irregular, the area includes an altitudinal gradient with forest coverage ranging from 500 to 2000 meters above the sea level on both sides of the mountain ranges. The two slopes of this area have contrasting climate patterns, mainly due to the effects of prevailing eastern trade winds. The Caribbean Slope is humid and rainy throughout the year, with a short dry seadson between February and April. The Pacific Slope is much more seasonal, especially in the lower areas, where rainfall reaches 2500 mm per year and take place from May to December. This zone is home of many limited range species, including the Coopery-headed Emerald, which occurs only in Costa Rica.
Over 50 % of the bird species of this zone are near endemic. This lever of endemism is not surprising since the mountains of Costa Rica and Panama are separated form similar elevations to the north of south by sizeable geographic gaps. There are species with three different bio -geographical origins: North America, Montane areas of Mexico and northern Central America, and the Andes. The isolation of the high mountains favored the formation of new species and, as a result the zone has the largest number of endemic species of the country (52 species, belonging to 23 families), that is also the largest number of endemic species in Central America. Species like Volcano Junco, and the Black Bellied Nightingale thrush only live at the highest areas of the mountain
Once moving inland from the Caribbean coast one eventually encounters the base of the mountains and the very wet foothill belt. As the moist air coming in off the Caribbean Sea reaches this obstacle, it rises and, in doing so, cools. The result is a lot of rain. Some sites in this zone can receive more than 20 feet of rain annually. The forest at this zone up to 1000 m elevation supports localized populations of Purplish-backed Quail-Dove as well Snowcap, Black and Yellow Tanager, Yellow-eared Toucanet, Red-headed Barbet, Prong-billed Barbet, Black-crested Coquette. The high diversity of environments along a broad altitudinal gradient contribute to this diversity of birds.