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It once was relatively easy to decide which coffee variety was least harmful to birds, but a new study of rainforest birds in India’s Western Ghats region reveals things are not as simple as they once seemed
I spent my university years in Seattle, a coffee-worshiping city. But as an ornithologist, I worried about the conflicts between the coffee I drink and the birds I study and work with. Which coffee is better for the birds: shade grown or sun grown? I wondered. At first, the answer seemed obvious: since pristine rainforests are being knocked down to make way for sun grown coffee monocultures, it wasn’t difficult to imagine that the vast, intricate webs of animals and plants that depend upon these biodiverse forests also perished. So I favored shade grown coffees.
Arabica versus robusta
Coffee is one of the most valuable and widely cultivated crops throughout the tropical regions of the world. Although there are more than 123 known species of coffee, and more are described every year, Coffea arabica (“arabica”) accounts for 60 percent of the world’s commercial coffee crop, whilst Coffea canephora (“robusta”) accounts for about 40 percent. Commercially-grown coffee is either shade grown where coffee bushes are interspersed throughout native forest — a low-intensity farming method that is common for arabica production — or it is grown in full sun monocultures — typical for robusta production.
During the last 20 years, shade grown coffee production has abruptly dropped, mostly due to increasing production of robusta, especially in tropical Asia. Climate change is also driving this shift from arabica to robusta. Although production is declining in the traditional coffee-growing regions in tropical America (the Neotropics) and Africa (the Afrotropics), global demand for coffee is still growing. But now, India is where the action is: India is currently the world’s sixth largest coffee producer and its total coffee acreage has more than doubled in the past 25 years.
From 1950 to 2015, the area planted with robusta coffee increased by 840% while arabica increased by 327% in India. Since robusta is grown in the sun, this requires significant changes to the landscape: removal of large old trees and removal of upper branches on other trees to open up the canopy — practices that had previously been identified as detrimental to the environment and to the birds and other wildlife living in these areas.
Most of India’s agricultural expansion has occurred in the Western Ghats — an ancient mountain range that runs along the western coast of the Indian peninsula. The Western Ghats is a biogeographically unique region, and is recognized as a global biodiversity hotspot because it is unusually species-rich and because it has an unusual number of species there that are found nowhere else in the world. Despite this, only one-quarter of this wilderness is formally protected from human exploitation.
How is this dramatic expansion of coffee production, especially sun grown robusta, affecting the birds living in the Western Ghats?
Birds and beans
A team of researchers from the Wildlife Conservation Society, Princeton University, and the University of Wisconsin-Madison examined avian habitat specialists living on arabica and robusta farms in the Western Ghats to learn which is the most “bird friendly” coffee. They also examined the effects on birds of changing a farm from arabica to robusta production.
Using household surveys of 61 arabica and robusta coffee farming estates across Chikkamagaluru, Hassan and Kodagu districts, the researchers found that the percentage of farmers planting coffee increased overall, and that the average acreage planted with robusta increased significantly during the past decade. They also found that both arabica and robusta were grown in dense rainforest under fairly closed — “shady” — canopies (average canopy density score of 94.6% for arabica and 79.2% for robusta.
When the birds were censused, the researchers found that bird communities in arabica farms were more species rich, and included a diversity of frugivorous, insectivorous, and omnivorous birds, and they had nearly twice as many endemic bird species when compared to robusta farms.
But robusta bird assemblages were more diverse than expected, especially when considering sensitive species such as frugivores. The team also learnt that only 19% of robusta farmers used pesticides compared to 75% of the arabica farmers, which allowed a far greater prey diversity and availability for insectivorous birds.
And of course, where ever there’s a diversity of birds present, you will find a diversity of other species too, many of which are harder to see, such as mammals, amphibians, and trees. This suggests that coffee farming in the Western Ghats may not be especially harmful to birds, wildlife nor indeed, to local biodiversity
“An encouraging result of the study is that coffee production in the Western Ghats, a global biodiversity hotspot, can be a win-win for birds and farmers,” said lead author, Charlotte Chang, who is an an ecologist “with theoretical tendencies”. Dr. Chang, who analyzed the data for this paper whilst a graduate student at Princeton University, now is a postdoctoral fellow with the National Institute for Mathematical and Biological Synthesis at the University of Tennessee, Knoxville.
Dr. Chang and her collaborators noted that coffee farms supported higher species richness, endemic richness and greater densities of birds overall when compared to other major cash crops produced in the Western Ghats, such as “betel nuts” from the areca palm, Areca catechu, and rubber, Hevea brasiliensis. Thus, although coffee production is increasingly changing the landscape, there is the possibility that carefully managed coffee farms can be less damaging overall to the existing biodiversity in the Western Ghats.
“Coffee farms already play a complementary role to protected areas in a country like India where less than four percent of land is formally protected,” said co-author Krithi Karanth in a press release. “Therefore, building partnerships with largely private individual and corporate land holders will provide much needed safe-passage and additional habitats for birds and other species.”
Although this study found that some birds do better in arabica farms than in robusta farms, Dr. Chang and her colleagues found both types of coffee farms were generally beneficial to local birds and wildlife — which is important since coffee farmers in the Western Ghats have been planting more of the hardier robusta recently.
As for me, I’m happy to learn that coffee farming is not as damaging to biodiversity as originally thought — well, in the Western Ghats region, anyway. That said, I’ll still drink arabica coffees because I think robusta coffee tastes rather like burned rubber tires. Since coffee farming is exploding in India, perhaps the farmers there will develop a new robusta strain that is less … robust?
Source:
Charlotte H. Chang, Krithi K. Karanth, and Paul Robbins (2018). Birds and beans: Comparing avian richness and endemism in arabica and robusta agroforests in India’s Western Ghats, Scientific Reports, 8(4):3143 | doi:10.1038/s41598-018-21401-1
