But it must be proven that this method of cultivation really does help maintain biodiversity, which is why scientists at the UK's Natural History Museum, like Dr Alex Monro, have been cataloguing hundreds of species on El Salvadorean coffee farms.
Coffee is a major cash crop for much of South and Central America.
Traditionally, coffee shrubs were grown under the shade of trees, but the arrival of pesticides and intensive farming methods in the 1970s led many countries to switch to clearing land and growing their coffee under full sun. But not El Salvador. Growing the coffee under the shade of trees and other shrubs provides an unlikely haven for birds, insects and rare plants. About 400 species have been recorded from shade coffee farms. Americans are very keen bird watchers, and so they're very keen to support the birds which they see in their country in the summer, which during their winter are actually living in Central America.