Compared with open farmland, wooded "shade" plantations（种植园） that produce coffee and chocolate promote greater bird diversity, although a new University of Utah study says forests remain the best habitat for tropical birds. The findings suggest that as open farmland replaces forests and "agroforests" -- where crops are grown under trees -- reduced number of bird species and shifts in the populations of various types of birds may hurt "ecosystem services" that birds provide to people, such as eating insect pests, spreading seeds and pollinating（授粉） crops.

"We found that agroforests are better overall for bird biodiversity in the tropics than open farms," says study author Çağan H. Şekercioğlu (pronounced Cha-awn Shay-care-gee-oh-loo), an assistant professor of biology at the University of Utah.

"This doesn't mean people should farm in intact forests," the ornithologist（鸟类学者） adds. "But if you have the option of having agroforest versus open farmland, that is better for biodiversity, with shade coffee and shade cacao [the source of cocoa and chocolate] being the prime examples."

Şekercioğlu's new study, funded by the University of Utah, is being published this month in the Journal of Ornithology. He will present the findings on Aug. 9, at the Ecological Society of America's annual meeting in Portland, Ore.

If consumers wish to support bird diversity and agroforests, "a good way is by choosing certified, bird-friendly, shade coffee or shade chocolate," he says. While such coffee or chocolate often cost more because they are more labor-intensive to produce, the certification "is usually better for the farmers' income as well."

He adds: "There are trustworthy environmental organizations that certify shade coffee," including the Smithsonian Institution, the Rainforest Alliance and the Rainforest Action Network.

Other crops grown in shade include cardamom（小豆蔻）, which is a spice, and yerba mate（巴拉圭茶）, which is steeped in（沉浸于） hot water to make a beverage popular in South America.