Bakermans, M. H., A. C. Vitz, A. D. Rodewald, and C. G. Rengifo. 2009. Migratory songbird use of shade coffee in the Venezuelan Andes with implications for the conservation of the cerulean warbler. Biological Conservation 142:2476-2483. doi:10.1016/j.biocon.2009.05.018
Most studies of birds in shade coffee have concentrated on numbers, species composition, and foraging dynamics, but none has looked at whether birds using shade coffee improve in body condition during the winter months. Body condition is strongly correlated with annual survival, and thus a crucial metric.
This study took place in Venezuela’s northern Andes near La Azulita in the state of Merida. This region is not very well represented in the literature (either coffee-growing or bird ecology research), yet it is an important wintering site for many North American bird species. These include various flycatchers and thrushes (Contopus and Catharus sp.), and a number of warblers including Cerulean Warbler (Dendroica cerulea). This species, which I have written about before, has declined an estimated 83% in the last four decades. The shade coffee farms examined ranged from 3 to 5 ha with 38 to 63% canopy cover. Nearby primary forest was also included in the study.
The four most common North American migrant species found, all warblers, were American Redstart, Blackburnian Warbler, Cerulean Warbler, and Tennessee Warbler. These species were three to fourteen times more common in shade coffee than in primary forest, even when detectability was factored in (because coffee farms are more open, birds can often be easier to detect, which would introduce bias if not accounted for).
Body condition was measured using various parameters in the five most common species of birds captured for banding in the shade coffee farms. Body condition improved over the winter for three species, including Cerulean Warblers, and was maintained in the other species. Nearly 30% of the individuals of the 15 species of migrants banded were recaptured, meaning they stayed in the coffee farms for prolonged periods of time throughout the season. These are all indications that the shade coffee provided quality habitat for these species.
In addition, 65% of Cerulean Warblers banded the first winter were recaptured or resighted the next winter, a remarkable return rate. Faithfulness to wintering sites is advantageous in that birds are familiar with resources such as food and cover, which can improve survivorship. However, it is also quite risky for birds wintering in areas experiencing high rates of habitat loss. Venezuela has seen nearly 40% of its shade coffee converted other types of agriculture — the authors state that they witnessed several shade coffee farms turned into cattle pasture during the two year duration of this study.
Just noting the sheer numbers, or even diversity of birds, in a particular habitat doesn’t tell the whole story. They may be present, sometimes only briefly, depending on the availability of resources in the larger landscape. This study not only showed that migrant birds were very common in shade coffee even in a region with primary forest, but also demonstrated site fidelity and improvement in body condition — adding a critical component to the story of the value of shade coffee.
Cerulean Warbler photo by Petroglyph under a Creative Commons license.
Bakermans, M., Vitz, A., Rodewald, A., & Rengifo, C. 2009. Migratory songbird use of shade coffee in the Venezuelan Andes with implications for conservation of cerulean warbler Biological Conservation DOI: 10.1016/j.biocon.2009.05.018
Revised on November 14, 2019
Very interesting. Thanks for sharing. Is Venezuelan coffee available in the US? I don't think I've ever seen it.
Apparently most of it is consumed within Venezuela. Since the oil boom, coffee has not been an important export there (a brief overview at Coffee Review). I've seen it offered a few times, mostly in dark roasts which tells me that what is showing up here might not be the best quality. It may be making a comeback, so we'll have to see what the market brings.
Venezuelan coffee beans are surely unique. We have gotten our hands on them in the past to sell in our organic store but as of late we have a hard time buying bulk.
SS
It's good to know that the shade coffee plantations do benefit birds' health. I wonder how well the results of the Venezuelan study represent the habitat quality in other coffee areas.
Studies are finding that by allowing the epiphytes to grow on the palm trucks, there is more structure and potential habitat. This practice — actually less work for the farmers — is correlated with higher bird and butterfly diversity.
The same study, though, also shows clearly that even with these enhancements, the biodiversity within palm oil plantations is far less than the biodiversity within primary and secondary forests.
So indeed shade grown coffee is the finest example of such biodiversity and very beneficial for birds as a natural habitat.
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