The blue-throated hillstar (Oreotrochilus cyanolaemus) is a hummingbird found only in a small portion of the southwestern Andes in Ecuador.

[2][3] The species name "cyanolaemus" is based on the Latinized Greek words for ultramarine blue (kuanos) and throat (laimos).

[4] The top of the head of the male blue-throated hillstar is iridescent emerald green, which extends from the forehead to the base of the crown.

The nape of the neck, mantle, lower portion of the back, rump, and upperwing coverts are bright emerald green.

The throat and chin are speckled; the feathers are black at the base, whitish in the middle, and grayish olive on the outer half, with a dark green spot.

The flanks, belly, breast, and undertail coverts are grayish buff with occasional brighter olive green feathers, as are the ventral regions of the tail.

[4] The vocalizations of the blue-throated hillstar are similar to those of its congeners; they are highly variable, and include rapid titters of rising and falling frequency, and single noted calls consisting of an "up–down stroke".

[4] Blue-throated hillstars were frequently observed being chased away from perches by Shining Sunbeams (Aglaeactis cupripenni).

[4] No more than 750 individuals have been estimated to exist, and this population is highly threatened by fire, grazing, and gold mining.

The proposed area – spanning around 175,000 acres in Cerro de Arcos – will protect the blue-throated hillstar’s entire habitat in addition to critical páramo and cloud forest ecosystems, wetlands and important water sources.