The supposed "black-billed hermit", described as P. nigrirostris, was proven to be a mutant P. eurynome with an all-black bill.

Its dark throat whose feathers have lighter edges give the eponymous scaly appearance.

[5] The scale-throated hermit's breeding season in Brazil spans from September to March but has not been defined in the rest of its range.

They are often decorated with the lichen Spiloma roseum that stains the eggs and nesting female red.

The scale-throated hermit's song is variable, "but typically comprises 2–4 notes, e.g. 'tsi-tseee....tsi-tseee..' or 'tsi-tsu-tseeé...tsi-tsu-tseeé...' etc."

Though its population size is unknown and believed to be decreasing, it is common throughout its range and occurs in several protected areas.