They also have some of the world's highest deforestation rates, and some scientists assert that conversion to sun coffee is contributing to the deforestation. In recent years the populations of many of the migratory birds familiar to Americans have declined drastically. The North American Breeding Bird Survey shows an annual drop of two to six percent from 1980 to 1994 for the Baltimore oriole, the Tennessee warbler, and the Cape May warbler. Other migratory birds have suffered similarly. These birds winter in northern Latin America and summer in North America.
Scientists attribute their decline partly to the destruction of forests throughout the hemisphere.
Naturalists have long viewed shade coffee as an important habitat for wildlife, especially compared with other crops. From 1990 to 1994 a team from the Smithsonian Migratory Bird Center found more than 150 species of birds on shade-coffee farms in Chiapas, Mexico, with numbers of migratory species particularly high. Species diversity on well-shaded farms can rival that in a tropical forest. Sun plantations, in contrast, hold little appeal for wildlife. Research in Colombia and Mexico has found that sun farms have just a tenth as many bird species as do shade holdings.