All About Birds’ entry for the Eastern Screech Owl (Megascops asio) says in part:
If a mysterious trill catches your attention in the night, bear in mind the spooky sound may come from an owl no bigger than a pint glass. Common east of the Rockies in woods, suburbs, and parks, the Eastern Screech-Owl is found wherever trees are, and they’re even willing to nest in backyard nest boxes. These supremely camouflaged birds hide out in nooks and tree crannies through the day, so train your ears and listen for them at night.
The Eastern Screech-Owl is a short, stocky bird, with a large head and almost no neck. Its wings are rounded; its tail is short and square. Pointed ear tufts are often raised, lending its head a distinctive silhouette.
Eastern Screech-Owls can be either mostly gray or mostly reddish-brown (rufous). Whatever the overall color, they are patterned with complex bands and spots that give the bird excellent camouflage against tree bark. Eyes are yellow.
Eastern Screech-Owls are active at night and are far more often heard than seen—most bird watchers know this species only from its trilling or whinnying song. However, this cavity-roosting owl can be attracted to nest boxes or, if you’re sharp-eyed, spotted in daylight at the entrance to its home in a tree cavity.
Read on for more including screech owl calls.
More owls on Michigan in Pictures.