(The adjective "Stygian" means "of, or relating to, the River Styx", but is more widely applied to anything that is dark or dismal.)

The face is blackish with a pale border and a whitish forehead, and the head has long dark feathers that project upward as "ears".

The eye is shades of yellow, the bill blue-black to blackish, and the feet dark grayish or brownish pink.

The subspecies are substantially alike, differing mostly in the shade of the upperparts' streaks and somewhat in size.

Some extend the range of robustus to include the Colombian, Ecuadorian, and Venezuelan populations otherwise attributed to A. s. stygius.

[6] The Stygian owl inhabits a wide variety of landscapes from sea level to 3,000 m (9,800 ft) of elevation.

The diet also includes bats (which are seldom preyed on by other owls), some other mammals (like Hispaniolan solenodons[11]), frogs, and insects.