The long-tufted screech owl is 25 to 28 cm (9.8 to 11 in) long. Males weigh 155 to 194 g (5.5 to 6.8 oz) and females 174 to 211 g (6.1 to 7.4 oz). It is a fairly large and bulky member of Megascops, with stronger feet than most others. It occurs in three color morphs of which the brown one predominates over the gray and rufous. It has very prominent "ear" tufts. The upperparts of the common morph's adult are dark brown with pale, coarse, indistinct vermiculation; its crown is somewhat lighter. The brown facial disc has a darker border. The underparts are a mix of irregular bars, streaks, and vermiculation in shades of brown. The eye is pale yellow to orange-yellow, the bill greenish gray, and the feet pale grayish brown. The plumages of the gray and rufous morphs and the juvenile have not been formally described.
The long-tufted screech owl is found in the southeastern Brazilian states of Paraná, Santa Catarina, and Rio Grande do Sul, in Misiones Province of northeastern Argentina, and in adjoining northern Uruguay. It inhabits a variety of open and semi-open landscapes. Examples include sparse woodland, pastures with trees, the edges (but not interior) of dense forest, secondary forest, and woodlots near villages. In elevation it mainly occurs between 300 and 1,000 m (980 and 3,300 ft).
The long-tufted screech owl is believed to be a year-round resident throughout its range.
The long-tufted screech owl is primarily nocturnal. It reportedly hunts by dropping from a perch onto prey. Its diet includes arthropods and small vertebrates; rodents, birds, amphibians, and fish are known among the latter.
The long-tufted screech owl's breeding season is not well defined but apparently includes August and September. It nests in tree cavities, either natural or made by woodpeckers. The few known nests fledged one or two young, and the female alone apparently incubates the eggs. Almost nothing else is known about the species' breeding phenology.
The IUCN has assessed the long-tufted screech owl as being of Least Concern. It has a fairly large range, but its population size is not known and is believed to be decreasing. "Loss of habitat through overgrazing, burning and tree-felling represents greatest threat to species."
