Like other thornbills, Rainbow-bearded Thornbill has an extremely short bill for its size. These thornbills are best identified by the large white splotches at the tip of the outer tail feathers, their rufous crowns, and their overall large size. The throats of males also glitter with color in good lighting. Rainbow-bearded Thornbills typically forage individually and generally cling to flowers when extracting nectar. They also hunt for insects and when foraging on the ground, they flick insects into the air and catch them in their mouths or fly at their prey with bills opened. These hummers inhabit shrubby páramo, stunted woodlands, and rocky slopes below the actual páramo.