Here's a really interesting website that deals with conservation of North American warblers (amongst others) in their Central American wintering grounds, much of which are farmed as coffee plantations. Also has links for Bird-friendly Coffee, so can't be bad.
http://nationalzoo.si.edu/ConservationAndScience/MigratoryBirds/
http://nationalzoo.si.edu/ConservationAndScience/MigratoryBirds/