White-sided Hillstar

Identification

The white-sided hillstar is a small hummingbird, measuring 13 to 15 cm in length and weighing just 7.9 to 8.4 grams. Both sexes share drab brown upperparts, but males are far more striking below, displaying a brilliant shiny green gorget bordered in black that contrasts sharply with a white breast and belly. A distinctive wide blue-black stripe runs down the centre of the male's belly into the vent area. The somewhat rounded tail is bronzy black with white at the base of the outer feathers. Females are duller overall, with pale throats finely speckled with dark markings and greenish-black tails; their outer tail feathers show much white at both bases and tips. Both sexes possess a medium-length, slightly decurved black bill. Juveniles appear greyer than adults, with males showing a dark blue-green gorget at an early age.

Range & Habitat

This species inhabits the high Andes, ranging from central Bolivia's Cochabamba Department southward through Chile to the Biobío Region and into Argentina as far south as Santa Cruz Province. The white-sided hillstar favours puna grasslands dotted with dwarf shrubs, cacti, and Puya plants, typically at elevations between 1,200 and 4,000 metres, though it occasionally ventures even higher towards the snow line.

Behaviour & Diet

The white-sided hillstar exhibits altitudinal migration, with most individuals leaving Chile during the Austral winter, though some simply descend to lower elevations. Occasional movement further north into Bolivia has been recorded in late winter and early spring. While specific details about this species' feeding ecology remain limited, it is believed to share similar habits with the closely related Andean hillstar: it feeds primarily on nectar from flowering shrubs, cacti, and trees, typically perching rather than hovering while feeding. It also gleans small arthropods from vegetation and occasionally captures them in flight.

Breeding occurs in November and December, when pairs construct distinctive large cup nests glued to vertical rock faces in well-protected locations. Clutch size is two eggs. The species produces a repeated short "tsit" call and engages in fast twittering vocalizations during chasing and display interactions.

Best Time & Places to See It

The white-sided hillstar is generally common throughout its range, which spans several protected areas. The austral spring and summer months (November to February) are optimal for observation, particularly before the species' winter exodus from the Chilean portions of its range. The puna grasslands of Bolivia, Chile, and Argentina where it resides offer excellent opportunities for viewing this striking hummingbird.

Photography Tips

Photographers should position themselves near flowering shrubs and Puya plants in puna habitats, where birds perch to feed rather than hovering. Early morning light will best illuminate the male's brilliant green gorget and contrasting black border. The bird's small size and high-altitude habitat demand fast shutter speeds and patience. Look for birds along vertical rock faces during breeding season (November–December), as nest sites may reveal regular feeding routes and perching spots ideal for portrait photography.