This species occurs in both morphs, brown and rufous, but the latter is very rare.
Male and female are similar, but the female is slightly larger than male.
The adult has brown plumage overall. The upperparts show dark-tipped white spots on scapulars. The tertial flight feathers are barred white and the tail is barred with narrow pale bars.
The upperparts are variably streaked and barred blackish-brown. The underparts are paler with dark brown to black streaks and white spots.
On the head, the inner parts of the facial disk are whitish, and the rest varies from rufous-brown to greyish. The head is brown, finely spotted white, including the short but prominent ear-tufts.
The bill is horn-coloured to brownish. The eyes are yellow. The greyish to brownish-yellow legs are feathered. The toes and the claws are fairly weak.
The
Sulawesi Scops-owl is resident in humid forests, clearings and edges. The species occurs from lowlands and hills up to 2500 metres of elevation. It is also found in cultivated areas with scattered trees and in scrubby areas.
The Sulawesi Scops-owl is a nocturnal species, becoming active at dusk. It spends the day in tree where it sleeps and rests, perched at about two metres above the ground or in the lower canopy, close to open areas such as clearings, ponds or rivers.
It feeds primarily on nocturnal insects such as moths, beetles and crickets. It hawks the flying insects from a perch. In these Asian regions, geckos are often active and abundant at night, and the Sulawesi Scops-owl could take advantage of these easy preys. It probably feeds also on small vertebrates.
The owls of genus Otus are usually monogamous and have long-term pair-bonds. To strengthen or renew the pair-bonds, the male begins singing 3-4 weeks before the nesting period starts. Courtship feeding by male to female is also a typical behaviour in owls.