The Dull-blue Flycatcher breeds in deciduous mountain forest, invariably above 600m, although it is not common below 900m. The main breeding season is in March and April, but a second brood is often reared later in the year.
The cup-shaped nest is a lined compact mass of moss. The site is usually a well-shaded rock ledge. The normal clutch is two or three brown-spotted pink eggs are laid. One of the best places to see this species is Horton Plains National Park.
This species is 15cm long. It is similar in shape to the Spotted Flycatcher and has a loud melodic song.. Adults are ashy blue, with a whitish belly. There is a black patch between the broad black bill and the eye, bordered with brighter blue above and below. Sexes are similar, but females are slightly duller.
Juvenile Dull-blue Flycatchers are brown, heavily spotted on the head, back, wing-coverts and breast with pale buff; their flight feathers are broadly edged with blue-grey.
This is relatively easy bird to see, despite its forest habitat. It feeds mainly on flying insects, beetles, caterpillars and other insects, but also eats berries.