Wednesday, May 12, 2021

Long eared owls always look surprised

Long Ear OwlOwls are birds of prey of the order Strigiformes, which are divided into two main families. Strigidae has 220 wide ranging species, for example round faced owls filling all possible sizes between the great horned owl and the elf owl. Tytonidae has 20 species, distributed worldwide everywhere but the polar regions and northern regions from Canada through eastern Russia, for example, heart faced owls like the barn owl.

Eight owls are found in the Adirondacks: Snowy owl seasonally, Great Horned owl, Barred owl, Long eared owl, Short eared owl, Barn owl, Eastern screech owl and Northern saw whet owl, all year-round residents.

Ancestors of Strigiformes, or true owls, show up in the fossil record up to 68 million years ago, three million years before the crashing of a comet into the Yucatan Peninsula, resulted in the extinction of all large dinosaurs and mammals over 50 pounds. Tytonidae go back about 58 million years. Birds are the direct descendants of dinosaurs, essentially what is left of theropod dinosaurs

Long eared owls look like a smaller version of the Great Horned Owl, which decided to go on a crash diet, and appears perpetually startled at the result, but they differ from their Strigidae relatives in several important ways. Medium sized owls between 14 and 16 inches long, weighing half a pound to a pound, and with a wingspan of about three to three and a half feet, long eared owls are more communal and less strictly territorial than other Strigidae, seeming to move around based on the availability of their most common prey, voles and other small rodents.

Long Ear OwlThe most striking feature of long eared owls are their plumicorns or ear tufts, which are longer than those found on great horned owls, and closer together on top of the head. We really do not know the evolutionary purpose of ear tufts, even though there are 55 species of Strigidae which feature them. The most supported explanation is that ear tufts break up the outline of nocturnal owls, which roost by day, aiding in camouflage, allowing the motionless owl to blend in against its background, which is mainly bark, branches and thickets. 

Some experts posit that the ear tufts, which have nothing to do with hearing, and are so called because of their position on the owl’s heads, make the head appear larger and more forbidding, resembling a mammalian predator’s head, but it seems to me that the most intimidating feature of owls are their disproportionately enormous eyes, a feature mimicked by certain bugs, caterpillar and fish, which feature large spots that appear to be eyes evolved to impress would be predators. There are suggestions that the position of ear tufts indicate mood, but I am not aware of any studies which indicate that. I have noticed that whenever I have handled a long-eared owl on a falconer’s glove, its ears are stiffer and more erect than when they are roosting. Perhaps all these observations play a role. Female owls seem to respond to courtship displays, while alarmed or aroused owls threaten with loud bill snapping.

Great gray owls look handsome, great horned owls threatening, but long eared owls look surprised, their enormous eyes framed in a round face on their neckless ovoid frames, the ear tufts straight up and down like exclamation points. The facial disk, with its ruff feathers suggest a faded orange, while the bristle feathers around the bill and between the yellow to orangish eyes form an off white “X”. The feathers of the upper breast resemble a blotchy vest, while the lower breast has lighter vertical brownish patches, sometimes in a feathery scaled appearance. Female feathers tend to be somewhat darker than the males, perhaps making them harder to spot while sitting on a nest. Owl’s legs are longer than they appear to be, sometimes as long as their body’s length, with much of the leg hidden under the owl’s plumage. Legs are feathered down to the large talons.

Migratory in their more northern range only, the breeding territory of long eared owls in North America stretch from about 100 miles inside the coast of British Columbia down the west coast of the United States, north from a thin southern slice of the Yukon, east touching the southern tip of Hudsons Bay, extending all the way to Nova Scotia on the east coast. south to New Mexico and Arizona, then swinging north through the Midwest to the great lakes. Wintering is done in the rest of the Southeast of the U.S. and in Mexico. Europeans and Asian ranges fall within the same general latitudes. Long eared owls live about ten years in the wild, much longer in captivity, where starvation is removed as a threat.

Long eared owls are not territorial the way most owls are, moving around to areas where prey is most abundant. During the non-breeding season, long eared owls roost by day in thick woodlands at the edge of hunting areas, often sharing a tree which provides good cover, all trying to blend in with tree trunks, branches, and thickets, sometimes in multiple trees in groups of nearly 100 birds. A group of long eared owls is called a parliament. Like screech owls, long eared owls will stretch and twist their torsos to resemble branches or snags on trees. Long eared owls must be adept at flying through dense forest to reach hunting grounds. 

Long Ear OwlThey hunt by night, perching and diving at movement or sound, but they also glide and flap, cruising over clearings, open fields, and riparian areas, only about six feet off the ground, sometimes hovering, before diving on their prey. In the Adirondacks, prey will usually be small to medium sized rodents like voles, white footed mice, squirrels, chipmunks, and rabbits, as well as small songbirds, such as juncos, bluebirds, oven birds, thrashers and occasionally mourning doves and grouse. They will also take invertebrates, reptiles, and amphibians. Prey are killed or immobilized by the sharp talons and bill. Smaller prey is swallowed whole or brought back to the nest in the bill for sharing. Larger prey is torn apart or carried in the talons back to the nest.

As with other owls, the eyes are not spherical, but rather long and tubular, locked into the sclerotic rings of the eye sockets, such that an owl cannot move the eyes independently, having to turn its head in a 270 degree sweep on 14 neck vertebrae, twice the number humans have. Both eyes face front, giving owls superior binocular vision for greater depth perception in determining the location of prey. The eyes are dominated by motion sensing rods over color detecting cones, so the emphasis is on detecting movement of prey rather than discerning color differences.

Hearing is the owls secret weapon, and most critical in locating the exact location of prey. The ears are located right behind the eyes in the facial disk, and are staggered, with the right ear larger and higher on the disk than its counterpart on the left, with the result that sounds below or to the left, land on the left ear microseconds before landing on the right. The owl turns its head through its medial and radial axis, until the two sounds coordinate, and because the eyes cannot be moved independent of the motion of the head, the owl must at that point be staring at the prey’s location. This triangulation of the prey’s location is dynamic in the sense that as the owl and the prey continue to move, the prey’s changing location is constantly updated, such that the long-eared owl is even more adept at locating prey in the dark than barn owls are.

As with other owls, flight feathers of long eared owls feature tiny comb like serrations on the lead edge, as well as soft fringes on the outer edge, which break up the sounds of flight, enabling silent flight, such that prey targets cannot hear the owl approaching, just as the owl is not distracted by the sounds of his own flight, while triangulating the positions of moving prey.

Most birds have crops for storing food for later consumption. Owls do not. They also lack the teeth of mammalian predators, so prey must be torn apart using the sharp talons and beak. Owls cannot digest bone, feathers, or fur. Prey are usually swallowed whole or brought back to the nest in the beak or talons to be shared. 

The owl’s digestive system is composed of the smaller proventriculus, which produces enzymes, mucus, and acid, which begin the digestive process, and the larger ventriculus or gizzard, which separates the indigestible parts, forming a pellet, which is stored in the proventriculus before being regurgitated by the owl hours later. The long-eared owl cannot swallow prey again, until the two-to-three-inch gray oval pellet is ejected.

During the breeding season, long eared owls seem to become communal, sometimes nesting only about 50 feet apart, other times three or four nests per square mile, in territories which rarely exceed a third of a square mile. They do not build their nests, often appropriating them from crows and magpies, but will add bark strips, leaves, feathers, and moss to cushion the nest. Researchers have determined that the owls nesting near each other are not related, which may explain the distribution of nests, being originally placed by corvids, and then taken over by the owls, rather than a desire to nest near relatives.

As with other owls, a long-eared owl which feels threatened, will flare her flight feathers, puffing up in a threatening manner with lowered head, attempting to look much larger than she actually is.  They will attack, talons outstretched while screeching at aggressors. Long eared owls are preyed upon by great horned owls and barred owls, while nests are raided by raccoons, martens, and black bears.

Long eared owl courtship begins in January in the Adirondacks with males calling to females with a series of “hoos”, which resemble the sound of a person blowing across the top of a bottle, about one “hoo” every three seconds, with the sound audible up to a half mile away. Females respond with a higher pitched sound like “veeee”. As they near each other, males will fly around above females, performing flight displays, occasionally clapping their wings audibly. The female may also fly around the proposed nesting site. If the female accepts the nest, the two will sidle up and preen and mate, sometimes on the ground, sometimes near the nest, which may be 10 to 50 feet off the ground. Wicker baskets may be placed in trees for ducks to nest in, which may be used by long eared owls.

The female will lay four or five white eggs, each about an inch and two thirds long, one every day or so, and incubate them for about 25 to 30 days. Chicks will hatch sequentially, eyes closed, helpless and covered in down, and will begin branching in about three weeks, crawling out of the nest to perch on nearby branches, while exercising their wings. Attempts at flight begin at about five weeks, with young becoming independent at about 2 months old, their coming and going from the nest attenuated by calls between young and parents. The male feeds the female during nesting and provides the food the female feeds to the chicks. The female joins in the hunt when chicks begin to branch and fledge.

All photos by Deb MacKenzie, provided by the Adirondack Wildlife Refuge

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Steve Hall

Steve and Wendy Hall run the Adirondack Wildlife Refuge and Rehab Center in Wilmington. They've been rehabbing and releasing wild animals for over 45 years, specialize in predators, keep wolves as the cornerstone of their educational program, and have lived in the Adirondacks for the past 20 years. The Adirondack Wildlife Refuge became a non-profit about 10 years ago.

Visit www.AdirondackWildlife.org to learn more.




One Response

  1. Vanessa Banti Vanessa says:

    I believe that Yoll the famous Russian internet owl is a long eared eagle owl :). She has a particular “uhoo” that she uses to communicate with her human. It must mean something in Russian. 😉

    Many thanks for the nice article Stephen!

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