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.