Cacao (the source of chocolate) grown under the shade of trees provides excellent bird habitat. And the birds provide a service to the cacao farmer by eating the bugs that eat the cacao shrubs.
Scientists tested the importance of birds in controlling insect pests by building mesh exclosures above 20 cacao shrubs on two cacao farms in western Panama. The exclosures kept birds from foraging on the cacao shrubs, but didn't affect insects. They also monitored 20 control plots, cacao shrubs without exclosures.
Inside the exclosures, large insects proliferated and caused significantly more leaf damage than in the control plots. Small insects were equally common in experimental and control plots and there was no difference in the number of new leaves grown.
Growing cacao under a canopy of shade trees is good for the birds, and good for the farmer.
This article summarizes the information in this scientific paper:
Van Bael, Sunshine A., Bichier, Peter and Greenberg, Russell S. 2007. Bird predation on insects reduces damage to the foliage of cocoa trees (Theobroma cacao) in western Panamá. Journal of Tropical Ecology, 23: 715-719
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