Birds are important visitors to coffee plantations because they prey on insects, like the coffee berry borer, that would otherwise harm the coffee beans or plants. In addition, pollinating insects are crucial for the fertilization of the coffee flowers, so they are also welcome visitors to coffee farms. But a new study, conducted by scientists from Latin America and the U.S., indicates that these two natural forces have more of an impact when they work together.
“Until now, researchers have typically calculated the benefits of nature separately, and then simply added them up,” said lead author Alejandra Martínez-Salinas of the Tropical Agricultural Research and Higher Education Center (CATIE) in Costa Rica. “But nature is an interacting system, full of important synergies and trade-offs. We show the ecological and economic importance of these interactions, in one of the first experiments at realistic scales in actual farms.”
Researchers manipulated visits by insects and birds to the coffee plants on 30 different coffee farms in the U.S. and Latin America. They excluded birds by covering the plants with large nets, and excluded pollinating insects using small lace bags that were placed over the flowers.
The experts set up four experimental scenarios: allowing bird activity alone (pest control), bee activity alone (pollination), no bird or bee activity at all, and finally, leaving trees in a natural condition, where bees and birds were free to pollinate and eat insects at will.
The results, published today in the Proceedings of the National Academy of Sciences, show that the combined positive effects of birds and bees on fruit set, fruit weight, and fruit uniformity – all important factors in determining quality and price – were greater than the sum of their individual contributions.
Overall, the study indicated that without birds and bees (and other pollinating insects), the average yield declined nearly 25 percent. This represents a reduction in income of roughly $1,066 per hectare, which would be highly significant for the $26 billion coffee industry. All those involved, including consumers, farmers, and corporations that prepare and package coffee, depend on nature’s unpaid labor for this popular product.
“These results suggest that past assessments of individual ecological services – including major global efforts like IPBES [Intergovernmental science-policy Platform on Biodiversity and Ecosystem Services] – may actually underestimate the benefits biodiversity provides to agriculture and human wellbeing,” said Taylor Ricketts of the University of Vermont. “These positive interactions mean ecosystem services are more valuable together than separately.”
The researchers were very surprised to find that many of the birds providing pest control in the coffee plantations in Costa Rica were migrants that had flown thousands of miles from Canada and the U.S. In fact, some spent their summers in Vermont, exactly where the UVM scientists taking part in this study hailed from.
The team is also studying how changing farm landscapes impact the ability of birds and bees to deliver benefits to coffee production. They are supported by the U.S. Fish and Wildlife Service through the Neotropical Migratory Bird Conservation Act.
“One important reason we measure these contributions is to help protect and conserve the many species that we depend on, and sometimes take for granted,” said Natalia Aristizábal, a PhD candidate at UVM’s Gund Institute for Environment and Rubenstein School of Environment and Natural Resources. “Birds, bees, and millions of other species support our lives and livelihoods, but face threats like habitat destruction and climate change.”
In addition to Martínez-Salinas (Nicaragua), Ricketts (USA), Aristizábal (Colombia), the international research team from CATIE included Adina Chain-Guadarrama (México), Sergio Vilchez Mendoza (Nicaragua), and Rolando Cerda (Bolivia).