This tiny bird is recognized by its yellow crown and blue-toned plumage. Small groups travel to places with abundant mistletoe berries.
It is about 8.6–9.6 cm long. Males have a bright yellow crown and much of the underside, with blue-toned throat and upperparts. Females are yellowish olive above and dull yellow below.
It moves in small groups toward places with abundant mistletoe berries. It mainly eats mistletoe and other tree-borne fruit.
In 2015 at La Selva, Costa Rica, a pair built a nest in an old woodpecker cavity in a wooden powerline pole, with the entrance about 8 m above the ground.
The La Selva pair carried rootlets, moss and other plant fibres as nesting material; both the male and female brought material.
At La Selva, the male dive-bombed a woodpecker and tyrant flycatchers that approached the nest cavity, and the intruders flew away.
An extinction-risk assessment has not been added yet.