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The tiny, bright yellow bird that John  James Audubon called “Wilson’s Flycatching Warbler” breeds in a large swath all across northern North America. Wilson’s Warblers winter in much of Central America, and so pass through most of the continent at some point during the year. Molecular studies have shown that certain breeding populations winter in specific geographic areas. For instance, the most northerly-breeding birds of the western population winter the furthest south in Central America.

Females have duller caps.

One of the original names of Wilson’s Warbler was “Pileolated Warbler” after the male’s striking black skullcap, or pileum. As one of the warblers that has a flattish bill bordered by specialized feather “whiskers” to aid in the capture of small insects, the descriptor of “flycatching” or “flycatcher” was added to its name several times through history. Because he was the first to formally publish a description, ornithologist Alexander Wilson is now honored in the common name.

In the breeding season, the typical habitat of Wilson’s Warblers is dense thickets, especially moist ones in riparian areas. In the winter, however, it can be found in a much wider variety of habitats, which are often more open than nesting habitats. It is most abundant in tropical forests, cloud forest, pine-oak forest, and forest edge habitat, and is frequently found on coffee farms.

While many bird species tend to be somewhat set in their behavior at certain times of the year, wintering Wilson’s Warblers may be solitary, either roaming through a locality or forming a territory, or found in mixed flocks of other birds.  In addition to insects and some fruit, nectar is also consumed in winter. This flexibility in habitat requirements, behavior, and food resources has no doubt contributed to the success of Wilson’s Warblers, which remain one of our most common warblers. Yet recent population trends indicate numbers have declined 2% a year in the U.S., and over 4% a year in the eastern U.S. in recent decades. This is a well-studied species, but we need to know more to understand how to best conserve them. Unfortunately, we often neglect to take action with common species until serious problems are evident.

We have found Wilson’s Warblers common on coffee farms we visited in Panama and Nicaragua. We are about to travel once again to Nicaragua, where we will spend time at Finca El Jaguar in Jinotega, and once again visit to Finca Esperanza Verde in San Ramon, Matagalpa. You’ll be hearing more about our trip soon!

Top male Wilson’s Warbler photo by David Hofmann, female by Jean-Guy Dallaire, and bottom male by Pablo Leautaud, all under a Creative Commons license.

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 [1]. 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.

[1] 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.

The Wood Thrush, a relative of the familiar American Robin, is often considered a symbol of the population declines of birds that nest in North America and winter in the tropics. This species has been declining since the mid-1960s, and is on the National Audubon Society’s 2007 WatchList of declining birds.

Wood Thrushes nest in forests over much of the eastern U.S. Like most other songbirds, they migrate at night. These thrushes travel an average of 2200 km between their nesting areas and wintering grounds in Central America.

In the winter, Wood Thrushes are most common in primary and mature second growth forests, and they can be a familiar site on polyculture shade coffee farms from Mexico to Panama. For instance, they are the most commonly banded species at the gorgeous shade farm Finca Esperanza Verde in Nicaragua — we caught and saw a number of them when we were there in March 2009.

One reason for Wood Thrush declines may be tropical deforestation. At least one study has found a correlation between reduced numbers of Wood Thrushes and reduction in forest cover in the northern portion of their wintering range [1].

Wood Thrushes will choose and defend a territory in the winter, much as they do when they are nesting. However, as forests are destroyed in the tropics (including for sun coffee), Wood Thrushes are forced to become nomadic — a case of too many Wood Thrushes and other species, and not enough space. These thrushes must move from place to place, or settle in habitat that is low quality. These birds are less likely to survive the winter than individuals who have territories in a good forest patch [2].

Here in North America, habitat fragmentation is considered another cause of Wood Thrush population declines. As in the tropics, Wood Thrushes can be found in small woodlots or low quality habitat, but their chances of successfully raising a brood are greatly diminished in these situations. In fragmented forests, predators are more common, as are Brown-headed Cowbirds, which lay their eggs in the nests of other birds, often targeting Wood Thrushes. These factors contribute to dramatic rates of nest failure in some locations.

The Wood Thrush and coffee connection is so iconic that this bird has been found on the coffee packages or web sites of Birds and Beans, Coffee for the Birds, Audubon Coffee, and Counter Culture Sanctuary Coffee, to name a few. Wood Thrushes are considered “area sensitive,” needing good, intact forests throughout their annual cycle. High-quality shade coffee plantations represent essential habitat for this species, and your choice of coffee has a direct impact on the survivorship of Wood Thrushes and other birds that rely on tropical forests.

Wood Thrush photo by Eddie Calloway under a Creative Commons License.

[1] Rappole, J. H., G. V. N. Powell, and S. A. Sader. 1994. Remote-sensing assessment of tropical habitat availability for a nearctic migrant: the Wood Thrush. In Miller, R. I. (ed.). 1994. Mapping the diversity of nature. Chapman & Hall, London, England.

[2] Deinlein, M. 1998. A “Sing”-ular Sensation. Wood Thrush: Bird of the Month. Smithsonian Migratory Bird Center.

One of the most enduring memories of my visit to Finca Hartmann is that of passing a spot that was frequently visited by a vivid male Violet Sabrewing (Campylopterus hemileucurus), a large tropical hummingbird found from southern Mexico to western Panama. Many of us in the U.S., especially in the east, think of hummingbirds as diminutive creatures. Violet Sabrewings, however, are big, spectacular birds the size of sparrows. The males are a brilliant dark violet while the females are largely metallic green. Both sexes have white-tipped outer tail feathers that flash as they hover and flit about. They are unmistakable and not soon forgotten.

Violet Sabrewings are most common at 900-1650 meters, the same elevations at which coffee is grown. These hummingbirds like open forests or edge habitats where they can find an abundance of flowering plants, and are found on most bird lists of shade coffee farms within their range.

Hummingbirds are among the most important pollinators, especially in the tropics. Many tropical plants have co-evolved with their specialized hummingbird pollinators, so that the flower is shaped in such a way that only a hummingbird with a matching bill can pollinate it. Violet Sabrewings pollinate a wide variety of flowers, and utilize a foraging strategy known as long distance traplining. They repeatedly visit flowers along a long, fixed route.

Coffee itself is rarely pollinated by hummingbirds (arabica coffee is self-pollinating, although fruit set increases when bees help cross-pollinate). Therefore, sabrewings and other hummingbirds are rarely found in sun coffee farms, but are reliant on the other flowering trees and plants found in shade coffee. Trees in the genus Erythrina are commonly used to shade coffee, and most tropical species are pollinated only by hummingbirds. Bananas and plantains, also frequently used in shade coffee, heliconias, and various ephiphytes are all very important to Violet Sabrewings and other hummingbirds. This plant diversity is not found in sun coffee, but shade coffee farms provide excellent habitat for these dazzling birds.

Another important feature for Violet Sabrewings found in shade coffee farms is nesting habitat. This species inevitably nests on the branch of a tree or shrub over a small stream (we found several nests near creeks at Finca Esperanza Verde). Some source of running water is characteristic of most coffee farms in Latin America, which use the washed or wet processing method. Without streamside vegetation, it’s unlikely Violet Sabrewings could nest successfully.

Another group of organisms depends on hummingbirds to complete their life cycle. Known as hummingbird mites, these tiny invertebrates live and reproduce in flowers, feeding primarily on the nectar. There is only one way for these specialists to move between plants: in the nostrils of hummingbirds. Mites that need to move to another flower of  their specific host plant (when the flower is dying) must clamber onto the bill and into the nostrils of a hummingbird in the brief few seconds the hummingbird is probing the flower. The mites recognize the scent of their host plants, and have an equally brief time to disembark into a new flower.

Hummingbird mites do not harm the birds; in ecological terms this is known as phoretic commensalism, when one species (the mite) uses another (the hummingbird) just for transportation. The mite benefits, the bird is not affected.

Swaths of sun coffee fragment hummingbird habitat, creating barren deserts essentially void of these beautiful birds, all for the want of a cheap cup of coffee. Save hummingbirds (and hummingbird mites!), drink sustainably-grown shade coffee.

Top photo by Jerry Oldenettel, second by Doug Greenberg, under Creative Commons licenses. Violet Sabrewing nest at Finca Esperanza Verde by Darrin O’Brien and Julie Craves, all rights reserved.

The Emerald Toucanet (Aulacorhynchus prasinus) is the most widely distributed member of the toucan family. It can be found from Mexico through Central America south to Bolivia. As might be expected for a species with such as broad geographic range, there are many subspecies — at least 17. They vary by throat color, facial pattern, and the color and pattern of the bill. Some researchers believe that some of these may actually be separate species, with perhaps four different species in Central America, and at least three in South America.

Emerald Toucanets are, as the name implies, smaller than toucans, at a little over a foot long. The sexes look alike, although males have slightly larger bills than females. Nobody is positive why this difference exists, as one study discovered it is not related to differences in diet or foraging (which is often the case when both sexes share territories year round). These toucanets nest in well-concealed tree hollows, and live in small flocks in the non-breeding season. They are found in open woodlands, including shade coffee plantations, from around 900 to over 3000 meters.

While they eat big insects and small lizards, fruit forms a large part of the diet of Emerald Toucanets. Therefore they are important dispersers of the seeds of tropical trees and shrubs. They have large feeding territories, so they encounter many species of trees, up to 47 at one Costa Rican study site alone. Although they are the smallest members of the toucan family, they’ll even consume large-seeded fruits, repeatedly regurgitating and reswallowing a fruit until the seed separates from the pulp and can be discarded. For the most part, seeds pass through the digestive system, though, and it’s been determined that those have a higher germination rate than seeds that merely drop to the ground in the fruit. All these factors make Emerald Toucanets an integral part of tropical forest ecosystems.

Because this species favors open forest habitats and forages in the mid-canopy, shade coffee farms are suitable habitat for them — and likely quite important in regions where other deforestation is high. Counter Culture Coffee chose the Emerald Toucanet for the new label of its Cafe San Ramon coffee because it is found at one of the main suppliers of these beans: Finca Esperanza Verde in the Matagalpa region of Nicaragua. In fact, when Counter Culture was redesigning the label and asked for a recommendation, I suggested this species (and the subspecies on the label is the correct one!). Just to keep myself honest, I’ll will be at Finca Esperanza Verde this week doing some bird surveys and bird banding, and hope to see a few Emerald Toucanets in the process.

Credits and references

Top photo of a “Blue-throated” Emerald Toucanet in Costa Rica by Laura Erickson; used with permission. Middle photo of the nominate form of Emerald Toucanet, in Honduras, by Brian Gratwicke, under a Creative Commons license.

Puebla-Olivares, F., E. Bonaccorso, A. E. de los Monteros, K. E. Omland, J. E. Llorente-Bousquets, A. T. Peterson, and A. G.
Navarro-Siguenza. 2008. Speciation in the Emerald Toucanet (Aulacorhynchus prasinus) complex. Auk 125:39-50.  For an excellent discussion of this paper and the taxonomy of Emerald Toucanets, see Nick Sly’s blog posts on the topic.

Riley, C. M. and K. G. Smith. 1992. Sexual dimorphism and foraging behavior of Emerald Toucanets Aulacorhynchus prasinus in Costa Rica. Ornis Scandinavica 23:459-466.

Wenny, D. May 2000. Seed dispersal, seed predation, and seedling recruitment of a newtropical montane tree. Ecological Monographs / Ecological Society of America, 70 (2): 331-351.

Wheelwright, N. T. 1991. How long do fruit-eating birds stay in the plants where they feed? Biotropica 23:29-40.

Wagner, H. O. 1944. Notes on the life history of the Emerald Toucanet. Wilson Bulletin 56:65-76.