The White-sided Hillstar is a hummingbird of rocky Andean habitats. Males have a blue throat and white underside, females a grey underside; both feed on nectar and insects.
The back is green. Males have a blue throat, black collar, and a black mark in the center of the white belly. Females have a grey underside and white corners on the dark green tail.
It lives alone or in pairs and feeds on nectar and insects. It spends summer in northwestern Patagonia; northward winter movement and torpor during cold periods are both reported as possibilities.
An extinction-risk assessment has not been added yet.