Song birds are negatively affected by urbanization and intensive management. The single greatest threat to the songbird's survival is the surge in aggressive sun-grown coffee production, now the most popular method of growing coffee in Latin America. Sun-grown coffee requires clearing the forest and removing the natural shade used by the songbirds and other creatures. It is a high input process useing chemical fertilizers and pesticides to enhance production. Migratory songbirds are dying by the thousands as a result of these practices. Shade-grown/organic coffee, on the other hand, used the forest's natural shade to produce coffee in the traditional manner from the natural, shade- loving coffee shrub. Many of the overstory trees are nitrogen fixers, enriching the soil which reduces the need for chemical fertilizers. Migratory birds thrive in this environment. By 1990, over half of the traditional coffee farms in Latin America had been converted to the sun-grown method of coffee production, permanently destroying songbird habitat and thousands of hectares of rainforest. Fewer than ten percent of the birds that thrive in shade- grown coffee farms can survive in sun-grown plantation environments.
Migrating songbirds need large tracts of undisturbed forest but have been forced to live in small, pocket-sized woodlands. As a result, their eggs are frequently eaten by forest-edge birds such as grackles, crows, and cowbirds. In addition, their eggs are eaten by cats and dogs from nearby urban areas, and by opossums, skunks, raccoons, and foxes, which avoid deep forests and thrive in suburban areas. Migrating songbirds, searching for undisturbed forests, expend excess time and effort. Further, dislocations make it difficult for them to fill all their needs, raise their young, and prepare for their winter migration.
In the UK the songbird population has fallen dramatically, with the corn bunting declining by 92 per cent in the 30 years since 1970. From 1950 to 1993, 65% of song thrushes disappeared from the UK.
Since the conversion of Latin American coffee production to sun- grown techniques, studies show that between 1980-1994 the songbird populations have steadily declined. The decline is dramatic: 30% fewer Baltimore Orioles, 70% fewer Tennessee Warblers and 50% fewer Cape May Warblers, are just three examples.
A survey sponsored by the US Fish and Wildlife Service shows drops among more than two dozen songbirds in the last decade ranging from 11 to 88 percent.