Although formerly considered a race of Long-tailed Sylph (Aglaiocercus kingi), the morphology, behavior, range, and altitudinal distribution of Violet-tailed Sylph classify it as its own species. It is common in cloud forests, especially in mossy areas and around 1000 meters in elevation; these sylphs also makes use of forest borders and partly open areas with shrubs and trees. The stunningly long outermost tail feathers of the male are purple with blue tips, distinguishing the male from the similar Long-tailed Sylph (Aglaiocercus kingi) which has a blue or teal tail in the area of range overlap. Violet-taileds usually forage near the ground, making repeated circuits to the flowers on vines, trees, or shrubs distantly spaced from one another. Some altitudinal migration occurs based on the flowering time of plants. They also gather insects from plants or by aerial hawking. A cursory observation might mislead one to believe that Violet-tailed Hummingbirds breed year-round, but they actually build nests outside of the breeding period (October-February) for the purpose of roosting.