The reddish hermit is 8 to 9 cm (3.1 to 3.5 in) long and weighs 1.8 to 3 g (0.06 to 0.11 oz). All subspecies are generally dark green and rufous on the upperparts and cinnamon rufous on the underparts. Males have a black band on the chest and the tail feather have narrow white or reddish tips. Females have lighter underparts than the males. P. r. episcopus is about the same size as the nominate but has orange-rufous rather than cinnamon-rufous underparts and white tips to the tail. P. r. nigricinctus is the smallest subspecies; it has the richest rufous underparts. P. r. longipennis is the largest subspecies. It has a whitish chin and its central tail feathers have rufous tips.
The subspecies of reddish hermit are distributed thus:
The reddish hermit is assumed to be sedentary.
The reddish hermit is a "trap-line" feeder like other hermit hummingbirds, visiting a circuit of many species of flowering plants for nectar. It also consumes small arthropods. Nectar robbing by piercing the base of a flower has been regularly observed in southeastern Brazil.
The reddish hermit's breeding seasons vary throughout its large range; in general in the north it is within May to October and in the south within October to February. The nest is a cone-shaped cup made of plant fibers, mosses, lichens, other plant material, and spider web. It is attached under a drooping leaf. The clutch size is two eggs and the female alone incubates them.
The IUCN has assessed the reddish hermit as being of Least Concern, though its population size is unknown and is believed to be decreasing. It has a very large range, is considered "locally common to abundant", and occurs in several protected areas.
