Boissonneaua flavescens is a hummingbird species found primarily along the humid montane slopes of the Andes, ranging from western Venezuela through Colombia and into northern Ecuador. It occupies elevations from approximately 5,250 to 9,800 feet, typically favoring cloud forests and forest edges, but it also frequents hummingbird feeders at forest lodges. This bird is considered plentiful across its range, and its conservation status is classified as Least Concern by the IUCN. There is no known migration pattern, as the species is considered sedentary year-round.

The species is recognized for its distinctive color combination: shimmering green upperparts with a bronzy crown and nape, a scaly green breast, and a broad rufous tail edged with buff and tipped with black. The underparts are white below the tail coverts, and the short, straight bill is black. Males and females appear similar. An interesting behavior associated with Boissonneaua flavescens is its tendency to hold its wings outstretched momentarily after landing, displaying a flash of rufous and brownish tones, a trait characteristic of its genus. It often perches on exposed twigs or branches and returns repeatedly to the same feeding territories. It feeds on nectar from native flowers and occasionally small insects, using rapid hovering flight.