Thursday, January 21, 2016

The Eastern Screech Owl


The most common owl in Ohio is the Eastern Screech Owl, Megascops asio, which occurs through all of Ohio and inhabits the eastern section of the US.

 Its optimum habitat is an area with scattered large trees with open woodlots interspersed with fields or pastures with a stream nearby. But, so long as there are sufficient trees the Eastern Screech Owl will live in most places. The suburban owls actually do better than their rural relatives due to increase in prey and a decrease in predators. The bird needs trees and will not survive without them, but will quickly recolonize an area once trees are replanted.

            The Eastern Screech Owl is the smallest owl that is likely to be seen in Ohio. With a length of eight and a half inches and a wing span of twenty inches it weighs in at just six ounces. The owl has ear tufts that are prominent if raised or will have a round headed look if lowered. There are two primary color morphs in the Eastern Screech Owl, a red (also called rufous) morph that is more common in southern Ohio and a grey morph that is more common in the northern portions of Ohio.
The grey morph is about seventy to ninety percent of the population of Eastern Screech Owls in northwestern Ohio.


There is also a much rarer brown morph that only makes up a small portion of the population in Ohio.

The Eastern Screech Owl is primarily nocturnal, meaning active at night, but may occasionally hunt at dawn, dusk, or even during the day. They will sit on trees and branches and wait for prey to pass by below to drop down on to. They can catch insects or bats on the wing, or snag fish and other swimming prey using their talons. When they move from perch to perch the owl will drop down before flying back up to another perch, forming a U-shaped pattern.

            The most common songs of the Eastern Screech owl is its monotonic trill or a descending whinny but it will also include barks, hoots, chuckles, rasps, and screeches along with a clacking sound by snapping the bill mandibles together. A good collection of the sounds an Eastern Screech Owl can make can be found at the Cornell University's ornithology website.


        The Eastern Screech Owl has a breeding population listed at around 900,000 with 95% of this within the US. The International Union for Conservation of Nature (IUCN) lists the Eastern Screech Owl at the conservation status of Least Concern (LC) and is in no current conservation danger but the North American Breeding Bird Survey estimate that the numbers may be declining by as much as 1% per year in the US.
         The Eastern Screech Owl is not a very picky eater and will eat a great variety of prey. This includes mammals ranging from mice and rats to squirrels and rabbits as well as many kinds of invertebrates. The owls will also prey on small birds and some larger birds and may even occasionally prey on bats and other screech owls.

        The owl will not build a nest of its own but instead nest in holes, such as those formed by broken branches or opened by wood peckers, fungus, rot, or squirrels. The owl will also accept nest boxes or other available resources (mailboxes, crates, etc.).
Nest heights can vary greatly, from just above the ground to over sixty feet high.

Egg-laying commences mid-March and is usually four white or off-white eggs. These eggs are incubated for about a month and the young leave the nest around four weeks after hatching.

            Some spotting tips to find Eastern Screech Owls would be to look for the owl pellets that will be found around the nests or commonly used roost, these pellets are the indigestible parts of prey such as the bones and fur. Areas frequented by the owls will also be stained by the whitewash, excrement, and will be another recognizable sign of a favored spot of the owls.
Smaller birds may also give away the position of the owls, as they may mob the roosting owl in large groups alerting other birds of the predator’s presence and trying to drive off the owl. These mobbing birds will give off agitated cries to the surroundings of the owl. But the easiest way to “see” if the owl is in your area would be to go out on a quiet night and listening for vocalizations, which can carry for very long distances.

Resources:
            wildlife.ohiodnr.gov
            allaboutdirds.org/guide/Eastern_Screech-Owl/id
            animals.nationalgeographic.com/animals/birding/eastern-screech-owl/
Picture resources;
            Eastern Screech Owl: http://flickriver.com/groups/1351214@n24/pool/
Screech Owl North American range: https://www.barnowlbox.com/screech-owl-biology/
            Nesting Grey and Red Morph: http://www.cleveland.com/neobirding/index.ssf/2010/03/post_16.html
            Red and Grey morph on branch (site mistakenly lists as Asio Otus, Long-Eared Owl, instead of Megascops Asio): http://www.wildlifesouth.com/Featured/2011/Eastern_Screech_Owl.html
            Tree with whitewash: http://letspaintnature.com/tag/how-to-find-owl-pellets/