This large tyrant flycatcher is found in savannah habitat with moriche palms. The nest is an open cup of sticks in the crown of a moriche palm, and the typical clutch is two cream-coloured eggs blotched with brown.
The adult sulphury flycatcher is 20.3 cm long and weighs 54g. The head and neck are dark grey, and there is a concealed yellow crown stripe. The upperparts are olive, and the wings and tail are brown. The underparts are yellow with a greenish tint to the upper breast and a white throat. The black bill is short and broad.
This species resembles the tropical kingbird, but is shorter, stockier, and has a shorter bill. The call is a loud squealing jweeez, quite different from the kingbird's twittering.
Sulphury flycatchers wait on an exposed perch high in a palm and sally out to catch insects in flight. They will also take some berries and other fruits.[2]
The species is in its own genus-(monotypic), because of its bird voicebox anatomy, the syrinx.
