Know Your Coffee Birds series

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 beautiful Baltimore Oriole (Icterus galbula) is a familiar summertime sight across eastern North America (as is its western counterpart, the Bullock’s Oriole, I. bullockii; the two were once considered the same species). Their cheerful whistled notes and distinctive bag-like hanging nests are characteristic of woodland edges, open areas with scattered tall trees, and mature suburban neighborhoods. The brilliant orange and black plumage of adult males (young males, females, and juveniles are all duller) make the Baltimore Oriole one of the most colorful and arresting species of songbird in North America.

One reason these orioles are so beloved is that they are easily attracted to feeding stations which offer grape jelly or oranges sliced in half. Baltimore Orioles are also conspicuous in spring and early summer as they feed on the nectar and pollen of the blossoms of flowering trees. Although during most of the nesting season they feed on insects, as do most songbirds, it is this affection for fruit and nectar that hint at the habits of orioles on their Latin American wintering grounds.

Trees in the large genus Inga are popular shade trees in Latin American coffee farms. They are fast-growing, evergreen, easy to prune, and fix nitrogen in the soil. While their overuse generally does not benefit biodiversity if they are planted at the expense of a variety of other trees, Ingas do have wildlife value. They produce an abundance of flowers in the dry season (our winter) to which many birds are attracted. Nectar and pollen are important food sources for birds during the dry season, when fewer insects are available.

The nearly ubiquitous presence of Inga on coffee farms almost always assures the presence of Baltimore Orioles on these farms in their wintering range as well. In fact, surveys in Chiapas, Mexico found more Baltimore Orioles in coffee farms containing Inga than in farms with more extensive tree cover or in mature forest.

In areas where coffee farms have been converted to sun coffee, Inga-shaded farms have become important refuges for orioles as well as other species. Small flocks of Baltimore Orioles, working their way through coffee farms in the mid-canopy of Inga are a frequent sight from Mexico through Central America. Other flowering trees that are often grown as shade trees in coffee farms, such as Erythrina and Gliricidia, are also visited by orioles and other birds. Many of these trees are pollinated only by birds and provide farmers with fuelwood and fruit in addition to shading their coffee. A fine example of the interconnectedness of coffee, shade trees, birds, and people in Latin America.

Top oriole photo from Wikimedia Commons, bottom by JimGuy, used with permission; map by Cornell Lab of Ornithology.

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.

The North American Wood Warblers are known for their colorful beauty. The male Black-throated Blue Warbler (Dendrioca caerulescens, left) is one of the most beautiful. This species is one of the most sexually dimorphic as well — the female is not blue at all — and was not even recognized as the same species until the late 1800s. The pale “hanky” showing on the lower edge of her wing, which matches that of the male, is the only giveaway.

This eastern warbler nests in large forests in the northeastern United States and southern Canada and in higher elevations of the Appalachian Mountains. They spend the winter mostly in the West Indies, as well as along the Caribbean coast of the Yucatan, Belize, and Honduras. New techniques using a simple laboratory test of the molecular composition of feathers has revealed that Black-throated Blue Warblers from the northern part of the breeding range winter mostly in Cuba and Jamaica, and birds that nest in the Appalachians winter mostly in Hispaniola and Puerto Rico [1].

A common species in shade coffee ecosystems
Wintering Black-throated Blue Warblers are frequently found on coffee farms, with studies noting them using these plantations in Jamaica, Puerto Rico, the Dominican Republic, Haiti, and Chiapas, Mexico. These studies often note that Black-throated Blue Warblers are one of the most common migrants found on the farms.

While wintering in coffee farms, Black-throated Blue Warblers consume primarily small insects, many of which are coffee pests. In Jamaica, Black-throated Blues were the number one predator recorded on the dreaded coffee berry borer.

Like some other species of wintering migrants, Black-throated Blues tend to segregate themselves by sex on their wintering grounds. Males tend to be found in tall, mature forest habitat, and females in shorter, shrubby habitat. Research has shown that in the Dominican Republic, shade coffee farms had more males than females [3,5], indicating that shade coffee farms were a good substitute for tall forest habitats.

Many bird species return to the same places to nest each year, and some also return to regular wintering areas. Black-throated Blue Warblers are very faithful to their wintering sites [2,3]. In fact, they have a stronger fidelity to their winter territories than their nesting territories, making the health of the habitats on coffee farms critical to their survival [4]. Declines in abundance of breeding populations in the southern Appalachians of over 2% a year the last two decades may be linked to severe habitat degradation in parts of the winter range, particularly Haiti [1] where deforestation is particularly severe.

The Black-throated Blue Warbler’s song is sometimes described as sounding like a buzzy “beer-beer-beer!” From its strong affiliation with shade fincas in the winter, we know what it really means is “coffee-coffee-coffee!”

[1] Rubenstein, D. R., C. P. Chamberlain, R. T. Holmes, M. P. Ayres, J. R. Waldbauer, G. R. Graves and N. C. Tuross. 2002. Linking breeding and wintering ranges of a Neotropical migrant songbird using table isotopes. Science 295: 591-593.

[2] Wunderle, J. M., Jr. 1995. Population characteristics of Black-throated Blue Warblers wintering in three sites in Puerto Rico. Auk 112: 931-946.

[3] Wunderle, J. M., Jr. and S. C. Latta. 2000. Winter site fidelity of nearctic migrants in shade coffee plantations of different sizes in the Dominican Republic. Auk 117: 596-614.

[4] Holmes, R. T. and T. W. Sherry.  1992.  Site fidelity of migratory warblers in temperate breeding and Neotropical wintering areas: Implications for population dynamics, habitat selection, and conservation. pp. 563-575. In: J. M. Hagan III and D. W. Johnston (eds.). Ecology and Conservation of Neotropical Migrant Landbirds. Smithsonian Institution Press.

[5] Wunderle, J. M., Jr. and S. C. Latta. 1996. Avian abundance in sun and shade coffee plantations and remnant pine forest in the Cordillera Central, Dominican Republic. Ornithologia Neotropical 7: 19-34.

Top male Black-throated Blue Warbler by Jerry Oldenettel; bottom by Julie Craves.