Owls are magnificent creatures that can be adorable companions and silent predators. The Eastern Screech Owl (Megascops asio) is in the Chordata phylum and are classified as vertebrates. This means at some stage of their development they have five distinguishing characteristics: a notochord; which is replaced with a vertebral column, a dorsal nerve cord, pharyngeal slits; which are not distinguished after birth, an endostyle, and a post-anal tail. Eastern screech owls are classified as deuterostomes, bilaterally symmetrical coelomates with a closed circulatory system.
Within the vertebrate subphylum, eastern screech owls are characterized as neognathae because of their feathers, beaked jaws without teeth, and keeled sternum where powerful flight muscles are attached. In appearance, the eastern screech owl is a short and stocky bird with a large head and short, almost absent, neck. They have rounded wings, a short, square tail, and are clearly distinguished by their pointed ear tufts that are usually raised. They range in color from gray to reddish-brown with patterns of bands and spots to blend into trees.
They have yellow eyes and their beaks are a gray-green color. Males and females seem similar in appearance, but the females tend to be larger in size. Their name is very misleading because their call is not a screech, but more of a whinny-like call with a low-pitched trill.
The eastern screech owl usually inhabits wooded areas near a water source in the United States, East of the Rocky Mountain range. They can live in natural or human-modified areas, so they are very common in suburban neighborhoods.
They use trees for camouflage and nest in or near the trunks. In some areas, people will put nesting boxes high in trees, and the eastern screech owl will make its home in these boxes. The eastern screech owl tends to be monogamous and the pairs will return to the same nest each year to mate and raise their young. They tend to be opportunistic predators and hunt mostly microtine rodents such as small mice, rats, chipmunks, squirrels, bats, and even moles. Their preferred diet usually consists of nocturnal animals or insects because the eastern screech owl is nocturnal and is an extraordinary night hunter. Small songbirds and larger birds like the Northern Bobwhite also make up 7% of the eastern screech owl’s diet. They also hunt and eat insects which aid in controlling the insect population of an area. By controlling the insect and rodent population they also prevent these animals from invading other species’ homes and prevent invasive birds from overtaking other bird’s nests. Daytime birds rely on the eastern screech owl for nest protection and aid in keeping native species in the area of the ecosystem.
While the eastern screech owl is a predator to many small animals, they are about the size of a robin bird. They average 6 to 10 inches in length and 18 to 22 inches for their wingspan. While they are great hunters, the eastern screech owl still lies prey to larger owls and hawks while their nestlings and eggs are preyed on by weasels, black rat snakes, skunks, raccoons, and American minks. Occasionally, the eastern screech owl will keep live Texas blind snakes in their nest to control ants and other insects that may invade their nests. The eastern screech owl is also susceptible to malaria and avian pox. They also have to combat pesticides and vermicides which can make them sick because they are at or near the top of their own trophic levels. These chemicals concentrate in the tissues of the animals the eastern screech owl is consuming which can cause birth defects, eggshell thinning, and even death to the adult owls.
As mentioned earlier, the eastern screech owl is monogamous and will mate for life, but they also exhibit a high mortality rate, so if their mate dies, or does not return to the nest when mating season comes around, they will find a new mate. The mating season for the eastern screech owl is usually between mid-March and late May and successful production of offspring leads to a lifelong pairing. After mating, the eastern screech owl has an oviparous reproduction strategy, where the female will lay a clutch of 2 to 7, usually 4, eggs over a period of up to a week, where she will lay one egg each day. The eggs are incubated entirely by the female for 30 days and depend on the male to provide food for her. Once the eggs hatch the hatchlings will also depend on the father for food until they grow a bit larger and their feathers come in to help them adequately thermoregulate, then the mother will also leave the nest and hunt for herself and her hatchlings. At around 28 days the hatchlings will fledge and start leaving the nest but cannot fly at this point, so they will hop around from branch to branch in their tree, this is called branching. After they have fledged and figured out how to fly, the owlets may stay with their parents for the next 8 to 10 weeks before leaving the nest for good. About 70% of the owls born in a single season will survive the first year. If they do survive, the oldest eastern screech owl recorded in the wild lived to be 14 years old, and in captivity, they can live up to 20 years old.
The eastern screech owl has a voracious appetite and they are not very picky eaters. Their diet consists of over 250 different critters, meaning their search for food is not very difficult, besides the use of pesticide and vermicides. Their hearing and sight are very exceptional, especially at night when they are on the hunt. During their hunt, they will perch in the trees silently listening and watching to pinpoint their prey before they swoop down with their sharp talons and snatch up their next meal. Their skills are so developed, they can even grab their prey straight out of the air. For larger, meatier prey they will use their beak to tear their bounty apart for consumption. After they have had their fill, the eastern screech owl will store more prey in their den for later consumption for themselves, or for their nestlings. Once the sun comes up the eastern screech owl gets comfortable to sleep. Occasionally they will wake up during the day to sun themselves for warmth but are obviously not awake to hunt or defend themselves against other prey.
Overall, the eastern screech owl is a fascinating creature with acute hunting skills and a very cute appearance. Their predator accuracy is admirable and they are amazing creatures that exhibit very unique ecological traits. They are in a high trophic level despite their size and will use their speed and agility to fulfill its niche within their habitats. Within the United States, there are about 680 thousand eastern screech owls, but that number is declining with the destruction of their habitats, increased use of pesticides, and human intervention. They are a wonderful pest population controller and protect the native species to an area. The eastern screech owl is the perfect animal for its niche, even though they are not often seen by people, but can be heard in neighborhoods.