Purple-backed Thornbill
Ramphomicron microrhynchum
Small hummingbird with an extremely short, straight bill. Males are unmistakable: brilliant purple above and green below. Females are green above and whitish below with dense green spotting, especially on the flanks. Both sexes have a fairly long, notched tail. Occurs in the Andes from western Venezuela to Peru. Usually seen singly in the canopy or borders of humid elfin forest near treeline, though can gather in larger numbers at flowering trees. Also ventures into páramo; occasionally descends to lower elevations in the dry season. Seasonal movements are not understood.
Identification
The purple-backed thornbill is 8 to 9 cm (3.1 to 3.5 in) long and weighs about 3.5 g (0.12 oz). Both sexes have a black bill, the shortest of any hummingbird. Males of the nominate subspecies have metallic violet-purple upperparts with a white spot behind the eye. Their gorget is iridescent golden green, the underparts bronzy green, and the undertail coverts coppery with tawny fringes. The tail is moderately long, forked, and dark purple. Nominate females have shining green upperparts, and like the male, a white spot behind the eye. Their underparts are white with green dots except on the belly. The tail is shorter than the male's and less forked, bronzy purple, and the outer pair of feathers have white tips. <p>Males of subspecies R. m. andicola have a green-bordered golden gorget and more rufous undertail coverts. R. m. albiventre is very similar to the nominate, but with lighter margins on the male's undertail coverts and smaller spots on the female's underparts. Males of R. m. bolivianum have metallic violet upperparts, dark green underparts, and grayish white undertail coverts.
Taxonomy
The purple-backed thornbill shares its genus with the black-backed thornbill (R. dorsale). It has these four subspecies:<p>Subspecies R. m. andicola and R. m. albiventre "are doubtfully distinct from [the] nominate."
- Scientific name
- Ramphomicron microrhynchum
- Authority
- (Boissonneau, 1840)
- Order
- Apodiformes
- Family
- Trochilidae
- Genus
- Ramphomicron
Range and habitat
The subspecies of purple-backed thornbill are found thus:<p>The purple-backed thornbill inhabits the edges of humid montane forest, Polylepis forest, páramo, and the transitions between them. R. m. bolivianum also occurs well below the treeline in shrubby areas. In elevation the species ranges from 1,700 to 3,600 m (5,600 to 11,800 ft).
- Migration
- Resident species
Behavior
The purple-backed thornbill moves from lower to higher elevations in the wet season.<p>The purple-backed thornbill forages for nectar from mid-level to the canopy, primarily by trap-lining. It has often been observed "robbing" nectar from holes in flowers made by Diglossa flowerpiercers. It has been recorded taking nectar from a wide variety of flowering plants, shrubs, and trees. In addition it feeds on insects caught on the wing and gleaned from flowers.<p>The purple-backed thornbill's breeding season has not been fully defined but appears to span from May possibly to December. It builds a cup nest of fine plant fiber with moss and lichens on the outside on a horizontal branch. The clutch size is two eggs and the incubation period 16 days.<p>The purple-backed thornbill's song is "a continuous series of quiet scratchy notes interspersed by short buzzes or dry trills." Its calls include "a short dry rattle 'trrr'..., a scratchy 'krr-kit', and a long twittering rattle."
Conservation
- Population trend
- declining
Photos
Distribution
Bird Calls
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