Revered or feared, owls are familiar to peoples around the globe, instantly recognizable by their upright stance and forward-facing eyes. The flat facial disk surrounding the eyes, and large, sometime asymmetrical ear bones, sharpen their hearing and ability to pin-point their prey during the night, when they usually hunt. Being birds of prey, they have a hooked bill and sharp talons on their toes. The Tytonid (masked) owls are easily distinguished from the typical owls (Strigidae) by their prominent heart-shaped (rather than circular) facial disks, and generally longer legs, as well as screeching calls. Of the 11 species of owls found in Java, only two are Tytonids, and the remaining nine are typical owls. Most owls nest in holes or crevices in trees, cliffs, or even buildings, and the females of all species lay white eggs. In many species both sexes incubate the eggs, while in others, the female incubates alone, but is fed by the smaller male on the nest. The chicks are covered in whitish down at hatching, and are fed by both parents.
Rarely seen, as normally active only at night unless discovered and mobbed by small birds. Silent wings, facilitated by soft plumage.
This family has a wide distribution on earth except Antarctica, most of them inhabit in the tropics. As a Strigiformes order member with Tytonidae, they share many features with their tytonids relatives. Optimize their sharp eye as a primary feature to spot their prey, pin it then grab with sharp talons and hooked. Broad and strong wing with soft but dense feathers produce silent wing beats. Easy to distinguished with tytonids by its circular facial disk then heart-shaped (see Tytonidae). Many of are recognizable by erectile tufts of feathers above their ears, and they do not function in sound acquisition). Of the nine typical owls in Java, only four species occurred in Baluran and they were rarely seen.