Comprehensive DescriptionRead full entry
The Volcano Hummingbird is endemic to the Central Cordillera in Costa Rica, and to the Talamanca Cordilleras of Costa Rica and western Panama. It occupies mountaintops from 1800 meters to the highest peaks, and descends as low as 1200 meters in the non-breeding season (Stiles & Skutch 1989). Individuals have a green back but exhibit clear sexual dimorphism that varies by region: males are distinguished by bright gorget color and the amount of buffy and black below the tail, which increase with latitude (Stiles & Skutch 1989). In contrast, females lack a colored gorget, have a white breast, and are slightly larger than males (Henderson 2002); average female weight is 2.8 g while average male weight is 2.5 grams (Stiles & Skutch 198), though both are approximately 7.5 centimeters in length (Garrigues & Dean 2007). Evolutionarily, mountaintops exist as genetic islands of suitable habitat, which contribute to regional variation within the species (Ditto & Frey 2007, Garrigues & Dean 2007). At these high elevations, the Volcano Hummingbird prefers to forage in montane forest and forest edges (including páramo), overgrown open areas, and gardens (Henderson 2002). Stiles and Skutch (1989) also note a preference for secondary growth resulting from volcanic eruptions, landslides, or human disturbance. Volcano hummingbirds are nectar-feeding trapliners, meaning they visit a regular circuit of the same flowers to forage (Gill 1988). Preferred nectar sources are a variety of small, often insect-pollinated flowers including Fuchsia, Salvia, Bomarea, foxglove (Digitalis), Indian paintbrush (Castilleja), blueberry (Vaccinium) and blackberry (Rubus), and Miconia (Henderson 2002). They will also filch nectar from tubular flowers in the territory of larger hummingbirds (Hilty 1994; Fogden & Fogden 2005). The Volcano Hummingbird enters torpor at night, a period when body temperature is lowered to near ambient to conserve energy (Bucher & Chappell 1997), and has a much faster metabolism than larger species (Wolf et al. 1975); a nesting female should visit about 2700 flowers per day to account for metabolic and foraging energy costs (Hainsworth & Wolf 1972). Stiles & Skutch (1989) observe that during the breeding season (August-February), female Volcano Hummingbirds construct compact cup nests decorated with moss and lichen on the outermost branches of trees and shrubs or dangling from overhanging banks facing south or east. Males are very territorial of desirable perches and surrounding foraging area and defend them with diving displays that include loud calls and wing snapping (Fogden & Fogden 2005; Clark et al. 2011). As with other high elevation species, the Volcano Hummingbird is sensitive to climate change that pushes suitable habitats further up mountaintops (Lawler et al. 2009).