The Blue-tailed Emerald is a small hummingbird that feeds mainly on nectar. By day it visits flowers in its territory and also takes flying insects or small arthropods from branches and spider webs.
The male has a green body and a metallic blue, forked tail. The female is smaller and paler green, with gray-white underparts, a white line above the eye, and white tips on the tail feathers.
It takes nectar from flowers and also catches flying arthropods or picks small insects from branches and spider webs. The guide reports that it usually feeds alone in Trinidad.
An extinction-risk assessment has not been added yet.