The Sibilant Sirystes is a tyrant flycatcher of South American forests. A taxonomic paper describes typical southern birds and paler populations in northern and central Brazil.
Typical southern adults have a black crown, gray cheeks, chin, throat, and breast, a pale yellow to gray belly, an olive back with dark shaft streaks, and dark wings and tail.
The study records the species in evergreen, semideciduous, deciduous, and riparian forests; it reports aerial sallies for insects and some participation in mixed-species flocks.
An extinction-risk assessment has not been added yet.