The Rufous-capped Warbler (Basileuterus rufifrons) is found through much of Central America, north through Mexico. This species is occasionally found in the southwestern U.S., when it creates a sensation among birders.
This warbler is a common resident of shade coffee farms all year long, where it can be the dominant foliage-gleaning species. This is a foraging method where birds pick off insects from the upper and undersides of leaves. Many birds that occupy coffee farms make the most use out of remaining forested patches, the canopy trees, and associated epiphytes — thus the importance of shade-grown coffee to birds. Rufous-capped Warblers are in the minority in that they also forage within the coffee layer as well.
Two of my former Rouge River Bird Observatory student volunteers co-authored a paper on Rufous-capped Warbler foraging habits on a shade coffee farm in Chiapas, Mexico . They knew from previous research that many resident species like the warbler that use shade coffee move to other habitats once wintering migrants from North America arrive, perhaps to reduce competition. Rufous-capped Warblers stay put, but shift from their foraging in all the layers of vegetation to focusing on the coffee and shrub understory in the winter. This is also likely due to competition for resources, since many North American migrants prefer to forage in the canopy layer.
This shift to lower foraging heights was in evidence when we visited Finca Esperanza Verde in Nicaragua, where we caught multiple Rufous-capped Warblers in the coffee production area, including the one photographed above.
This is just another example of the complex interactions between resident and migratory birds in the tropics, an intricate dance coordinated over thousands of years of evolution. The Rufous-capped Warbler has adapted well to shade coffee production. Let’s drink shade-grown coffee, and keep them around.
 Seasonal shift in the foraging niche of a tropical avian resident: resource competition at work? Jedlicka, J., R., Greenberg, I. Perfecto, S. M. Philpott, and T. V. Dietsch. 2006. Journal of Tropical Ecology 22:385-395.
Photo by Darrin O’Brien, all rights reserved, used with permission.