Birds in shade coffee: A visit to Panama

by Pam Owen, November 2006

What do shade-grown coffee, army ants, and Rappahannock's migratory songbirds have in common? They're all part of the fascinating ecology of Panama.

	A shade coffee plantation with intact forest in the background. Coffee grown in the shade of rainforest canopy offers more biodiversity than coffee grown in the sun on land that has been cleared of forest. Photo by Alan Williams.

Panama is located at the narrowest section of the Central American isthmus linking the North and South American continents. A World Bank study notes that, with coasts on both the Pacific and Atlantic, "the country has biogeographic and climatic factors conducive to a variety of habitats and diversity of flora and fauna." It is the only Central American nation with "globally important tropical moist broadleaf forest," according to the Bank. Two-thirds of the country falls within what is considered "the highest or high priority category of biodiversity." Panama is home to approximately 10 percent of the world's varieties of birds—930 species out of a total of 9,672. The Isthmus of Panama is the biologic bridge for 120 species of migratory birds.

Increased farming, road construction, mining concessions, native-forest exploitation, and other human activities threaten the ecological health of Panama. In the late 1990s, Shenandoah National Park Ecologist Alan Williams participated in a study funded by the Smithsonian Migratory Bird Institute that explored how habitat fragmentation from these activities affected migratory and resident songbirds in the country.

In spring 2006, Williams led a bird identification walk sponsored by the RLEP's Biodiversity Task Force. On the walk, he discussed the characteristics and habits of migratory songbirds that fly through or nest in our area in the spring and summer. In the Panama study, he and the other researchers had found many of those same birds—including Tennessee and other warblers, American redstarts, indigo buntings, and thrushes—overwintering in Panama.

Much of the Smithsonian study took place at Finca Hartmann, a small family-owned farm ("finca" in Spanish) in the Chiriqui highlands of the Talamanca Range, which is shared by Costa Rica. This area encompasses "the largest complex of protected areas and intact ecosystems within one bioregion in Central America," according to the World Bank.

While most coffee in the world is grown in the sun, where native forests have been replaced by coffee bushes, Williams says Finca Hartmann grows "shade coffee" beneath a canopy of forest that can vary between three trees per acre to almost a full canopy. Shade-grown coffee bushes, once established, take less care than sun coffee and live three times as long, he adds.

	A katydid on coffee cherries. Photo by Alan Williams.

Not only does this use of native forest produce great-tasting coffee, it also provides greater biodiversity than the areas that have been logged and then planted in sun coffee. The varying elevations of 4,000 to 6,000 feet at Finca Hartmann also add to the variety of habitat types and therefore to the biodiversity. The presence of more than 280 bird species have been recorded on the farm.

Williams says the increased interest in specialty coffees, especially those that have lower impact on the natural environment, has made shade growing even more attractive to Latin American farmers. Specialty coffee producers are increasingly interested in Panama shade coffees and will buy them before they are grown, allowing the farmers to invest more in their operations. The value of biodiversity and the aesthetic of having intact forest is also not lost on these farmers, says Williams. Although the market for specialty coffee is increasing, the Hartmann family has avoided relying on one crop by diversifying into other environmentally sustainable activities, such as environmental tourism, that will help protect their stunning, biodiverse surroundings.

Along with the upland area at Finca Hartmann, the team studied the lowland area around the Panama Canal. Because the canal requires a dependable flow of water from the surrounding watershed, a buffer area on either side of the canal has been protected (until recently, by the US military) from development, retaining much of its natural biodiversity.

	A Tennessee warbler with coffee cherries. This species passes through the Appalachians on its way to breed in Canada after overwintering in the tropical forests of Panama. Photo by Alan Williams.

The study showed, says Williams, that fragmented forests were clearly lower in biodiversity than intact forests. It also showed that resident birds were particularly sensitive to habitat fragmentation, with migrant birds more likely to winter over in fragmented sections of rainforest. The migratory species in general seemed more resistant to change, more adaptable. This gives hope to their future survival but does not bode well for the resident species.

As part of the study, the Smithsonian researchers also looked at the connection of birds to army ants, which also inhabit tropical rainforests. Army ants are fascinating insects that have not changed significantly since the reign of the dinosaurs, about 100 million years ago. They are swarm raiders, foraging in colonies of up to 2,000,000 adult individuals in dense, fan-shaped swarms that can span 10 to 30 feet across, attached to a temporary nest by a single column that can itself extend more than 600 feet. The Smithsonian researchers found three species of army ants in the study area.

Army ants are the most important predators in the tropical forests of Central and South America, killing every animal in their path that can't escape. One colony can kill more than one million animals per week, filling the same niche as a large predator, Williams says. Some bird species take advantage of the great disturbance the ants cause in the rainforest when on the move by preying on the animals that are fleeing just ahead of the swarms. These bird species are considered "ant obligates," or more commonly "ant birds." The researchers found that resident bird species were more likely to be ant birds than the migrants, who were more opportunistic—taking advantage of the prey the ants flush as they come through but not following them all the time.

On 14 November 2006, Williams gave a digital slideshow presentation on the Smithsonian study and discussed the connections between migratory songbirds, shade-grown coffee, and army ants. He gave some background on Panama's complex tropical ecosystems and what it's like to do research in the country.  Spicing up the presentation were photos of the spectacular tropical rainforest scenery and the birds studied, a video of army-ant swarms, and a sample of shade-grown coffee from Finca Hartmann, supplied by Central Coffee Roasters of Sperryville, Virginia.

For more information on biodiversity programs, contact Pam Owen at 540-675-9989 or Biodiversity@RLEP.org.