[3] Two subspecies of the tawny-bellied hermit are recognized, the nominate P. s. syrmatophorus (Gould, 1852) and P. s. columbianus (Boucard, 1891).

The central tail feathers of both sexes are long and white and the rest are dark with bright orange ends.

[4] The tawny-bellied hermit's breeding seasons across its range have not been determined in detail but seem to be in the March to August window and possibly also in December.

The nest is a cone-shaped cup constructed of leaves and vegetable fibers bound with spider silk and suspended from the underside tip of a drooping leaf.

[4] The IUCN has assessed the tawny-bellied hermit as being of Least Concern, though its population size is unknown and believed to be decreasing.