Length averages, wingspan, and weight. Weight ranges from. Females are larger than males and northern populations are notably larger than southern populations. Adults are larger than whiskered screech owls, with larger feet and a more streaked plumage pattern. There are several morphs: brown Pacific, grey Pacific, Great Plains, Mojave, and Mexican. All have either brown or dark gray plumage with streaking on the underparts. There is no red morph. They have a round head with ear tufts, yellow eyes, and a yellowish bill. Their appearance is quite similar to whiskered and eastern screech owls, so it is best to identify them by their calls. They were previously considered to be the same species as the eastern screech owl.
Call
The primary call is an accelerating series of short whistles at an increasing tempo or a short then long trill falling slightly at end. Other calls: barking and chuckling, similar to the eastern screech owl. They also make a high pitched screech. The two primary songs for the Western Screen Owl are the bounce and double trill. In a recent study, researchers utilizes sonographic analysis of tape-recorded vocalizations to analyze whether the songs differ in male and females and if so, how accurately could songs be classified by sex. It was discovered that on average, male bounce songs were ~30% lower in frequency than bounce songs of females. However, song duration, note duration, number of notes per bout, and internet duration did not differ. For trill songs, males were also significantly lower in frequency compared to those of females. In addition, female double trill songs had greater internet distances in the leading portion.
They are permanent residents of the northwest North and Central America, breeding in open woods, or mixed woods at forest edges. They often use holes in trees or cacti that were opened by woodpeckers.
Prey
These birds wait on perches to swoop down on unsuspecting prey; they may also catch insects in flight. They are active at dawn, night, or near dusk, using their excellent hearing and night vision to locate prey. Their diet consists mainly of small mammals such as mice or rats, birds, and large insects; however they are , even taking small trout at night. Motion-activated cameras have photographed the birds eagerly scavenging a road-killopossum. They have also been known to hunt , occasionally. Hatching of their young, usually four to five, is synchronized with the spring migration of birds; after migrants pass through screech-owls take fledglings of local birds.
