Slender-tailed Woodstar Microstilbon burmeisteri Scientific name definitions

Fairly little ecological information is available for this small hummingbird. Slender-tailed Woodstars are subordinate to other hummingbirds and inhabit shrubby slopes, thorny scrub, deciduous woodland, and thicket-filled ravines. They have notably quick wing beats and zoom around visiting high flowers. Males and females are bronzy green above with a short white stripe behind the eye. Males boast a reddish purple throat and white chest while females are mostly buffy below.

7–9 cm (including tail of c. 3 cm). Male has short, rather straight black bill; upperparts bronzy green; gorget reddish purple, flaring into long moustachial tufts, bordered below by white; rest of underparts pale greyish, throat and sides mottled green, undertail-coverts pale cinnamon; very narrow black tail is forked, with rectrices blunt-tipped. Eclipse male has pale throat. Female similar to male, cheeks dark, with small white postocular stripe; underparts cinnamon-buff with white patch either side of rump; tail short, square, central feathers green, rest cinnamon with black subterminal band. Juvenile resembles adult female.

C & S Bolivia (from SE Cochabamba and W Santa Cruz) to N Argentina (Jujuy, Salta, Tucumán). Old record from Yungas of La Paz (NW Bolivia).

Shrubby slopes, ravines with vine-tangled thickets, and patches of deciduous woodland at 1100–2600 m (1 Lane, D. F. (2014). New and noteworthy records of birds in Bolivia. Cotinga 36:56–67. Close ).

Seasonal altitudinal movements strongly suspected in Bolivia and has even been suggested that species might be an austral migrant (1 Lane, D. F. (2014). New and noteworthy records of birds in Bolivia. Cotinga 36:56–67. Close ).

Presumably takes insects and nectar from small flowers similar to those visited by Chaetocercus, recorded visiting flowering epiphytes. Forages at higher strata, with fast wingbeat giving the impression of a bumblebee; subordinate to other hummingbirds.

Poorly known. Calls while feeding and hovering include a series of dull “chip” notes, sometimes doubled. Wings make a low bee-like humming sound while hovering.

A nest in Tajira department, Bolivia, had two eggs in Jan and was in the branch of a tree c. 3 m above the ground (2 Budin, E. (1928). El nido del picaflor Chaetocercus burmeisteri. El Hornero. 4: 188–191. Close ). Another nest in Catamarca province, Argentina, containing two eggs in Dec, was in fork of horizontal branch of a tree, 6 m above the ground; the nest was cup-shaped, made of soft pieces of plants, externally covered with lichens, and bound and secured with spider web; the eggs were white, one measuring 10 mm × 7∙4 mm (3 de la Peña, M. R. (2001). Nidificación de algunas especies de aves en el este de la provincia de Catamarca, Argentina. El Hornero 16:17–21. Close ).

Not globally threatened (Least Concern). CITES II. Generally not uncommon to common, but often overlooked due to its small size and retiring habits. Life history virtually unknown; available evidence suggests it may accept man-made habitats to some extent, but further investigation required. Presence in Yungas of La Paz documented by old specimen; no recent records in the area. Occurs in Calilegua National Park (Argentina).