The Equatorial Pacific Seasonally Dry Forests of south-west Ecuador and north-west Peru (also known as the Tumbesian region) are amongst the most unique and biodiverse forests on earth. These forest habitats have evolved in isolation in a relatively constant climate maintained by the cold Humboldt current. With marked seasonal rains and dry seasons the area has developed a covering of deciduous tropical forest with many endemic species. The area is isolated by the Pacific to the west, the Andes to the east, the wet forests of the Chocó to the north and the Peruvian Coastal desert to the south. The constant climate and isolation has led to the evolution of many endemic species unique to the region. This endemism combined with high rates of forest cover loss in recent years has led to the area becoming one of the most threatened on earth with many species in danger of extinction.
The Equatorial Pacific Seasonally Dry Forests have been considered one of the three global conservation priorities (along with the Philippines and Atlantic Forests of Brazil) based on the high numbers of endemic and threatened species (classified as such by Myers, Conservation International, WWF, BirdLife International). The area supports 65 endemic bird species, 21 of which are considered to be globally threatened, and 9 endemic mammal species of which 6 are considered threatened. The area has similarly high levels of endemism in other taxa with up to 60% of the amphibians and reptiles being endemic.
The original coverage of the dry forests has been decimated through the past five centuries with the rate having accelerated with road building programs in the last half century. Now only approximately 4% of the original forest cover remains in good condition.