Heliothraupis oneilli was described from the lower Yungas of Peru and Bolivia. The study reports different recorded settings in the breeding season and dry season.
The described male is brilliant yellow, with a black line above the eye, a pinkish bill, and a burnt-orange crest. The female is also mostly yellow.
In Bolivia, the paper records breeding in deciduous forest during the rainy season, November to March, and movement to lower Andean slopes in the dry season. It suggests the birds may prefer shorter, drier ridges with Guadua bamboo.
An extinction-risk assessment has not been added yet.