The green-backed firecrown (Sephanoides sephaniodes) is a hummingbird in the "coquettes", tribe Lesbiini of subfamily Lesbiinae. It is found in Argentina, mainland Chile, and the Juan Fernández Islands.
Taxonomy and systematics
The green-backed firecrown is monotypic. It shares its genus only with the Juan Fernandez firecrown (S. fernandensis).
Description
The green-backed firecrown is long. Males weigh about and females about . The species is sexually dimorphic, with larger, short-billed males, and smaller, longer-billed females. Adults of both sexes have bronzy green upperparts, slaty green wings and tails, and pale buff underparts with black and green spots. Adult males have the eponymous iridescent red-yellow crown. Juveniles of both sexes have rusty feather edges on the head and their underparts have a cinnamon tone. Because the young are sexually monochromatic, it is difficult to assign a sex to them.
Distribution and habitat
The green-backed firecrown is found in Chile from south of the Atacama Region all the way to the southern tip of South America, in the adjoining areas of southern Argentina, and east across central Argentina to the Atlantic coast. (See Behavior:Movement below for details.) An isolated population is found on Robinson Crusoe and Alejandro Selkirk Islands of the Juan Fernández group, some off the Chilean coast. It has been recorded as a vagrant on the Falkland Islands. The species inhabits forest edges, plantations of introduced Eucalyptus, clearings, thickets, and gardens. It is an important pollinator for the temperate rainforest regions of southern South America. In elevation it ranges from sea level to above .
Feeding
The green-backed firecrown feeds on nectar from a variety of native and introduced flowering plants, favoring those of genera Abutilon, Embothrium and Fuchsia, and sometimes perches on flowers to feed rather than hovering. It is able to recall not only the nectar location among identical flowers but also to the location of the most rewarding nectar among less rewarding flowers. It is intensely territorial and has been noted to chase birds as large as caracaras.<gallery mode="packed">
File:Green-backed Firecrown, Ushuaia, Tierra del Fuego, Argentina imported from iNaturalist photo 362459841.jpg|Feeding from native Chilean firebush
File:Sephanoides sephaniodes 468387779.jpg|Perching while feeding from introduced Kniphofia
Green-backed firecrown (Sephanoides sephaniodes) female Tricao.jpg|female
File:Green-backed firecrown (Sephanoides sephaniodes) female in flight Tricao.jpg|female feeding in flight on Kniphofia
File:Sephanoides sephaniodes 483376296.jpg|Feeding from Abutilon
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Breeding
The green-backed firecrown's nesting season on the mainland spans from September to November; data are sparse but the season on Juan Fernández appears to be September to December. The nest is a very small cup that is sometimes placed above water. The clutch is two white eggs. Nothing else is known about the species' breeding phenology.