Asio flammeus
short-eared owl

Short-eared owls are one of the world's most widely distributed owls. They inhabit all of North and South America; this area includes the coast of the Arctic Ocean to Pantagonia. Short-eared owls can also be found on every continent except Australia and Antarctica. (Granlund et al., 1994; Welty, 1975; Pearson, 1936)

One of the world's most widely distributed owls, Asio flammeus can be found throughout much of North America and Eurasia. These owls prefer to live in marshes and bogs; they inhabit open, treeless areas. Their hunting and nesting habits make them well suited to relatively flat land. This species is migratory but uses relatively similar habitats during summer and winter. Short-eared owls have specialized eating habits and tend to stay where they can find ample food. They will leave an area to find preferred prey rather than eat other animals. Nests are usually located on dry sites and in open country supporting small mammals such as voles and lemmings.

(Martin, 1990; Sparks and Soper, 1989; Pearson, 1936)

Short-eared owls range in length from 340 to 415 mm in males (mean 373 mm) and 340 to 423 mm in females (mean 382 mm). Wing length is from 279 to 307 mm in males and 267 to 314 mm in females. Wingspan is estimated at 950 to 1100 mm. Males and females are not easily distinguishable from each other externally, but females are usually slightly larger. Their feathers are yellow-white and dark brown; parts of the head and especially the legs and flanks are white. Individuals vary considerably in colors. The right and left ears occupy different vertical positions on the sides of their head, but the size and shape of the two ears are the same. (Holt and Leasure, 1993; Martin, 1990; Pearson, 1936) (Wiggins, Holt, and Leasure, 2006)

Records are limited, but the longevity record for a wild short-eared owl is 4 yrs, 2 months. Causes of mortality include occasionally being hit by cars and airplanes, or being shot or trapped.

In contrast with many other owls, short-eared owls begin foraging during daylight or early evening. These owls may continue to be active into the night, but usually cease activity after nightfall. They have a tendency to form communal roosts during the winter months. In different times of the year, they may live alone or together, but they always hunt alone.

After breeding, a mated pair remains together for the current breeding season. These owls defend their territories during the breeding season through skirmishes and chases; the size of this area depends on food availabiltiy. (Holt and Leasure, 1993; Martin, 1990; Sparks and Soper, 1989)

The individual spacing of short-eared owls is poorly known, but owls in communal winter and post-breeding season often roost within 1 meter of each other. There is a wide range in the size of breeding territories. Short-eared owls are thought to be highly migratory in the northern part of their range, above around 50 degrees north latitude. Additionally, data indicates seasonal north/south migration and west/southwest movements for some individuals at mid-latitudes. Nomadism in search of food, migration, and juvenile dispersal may be confused.

Home Range

Breeding territories vary widely in size, depending on the density of resources in the area.

Short-eared owl nestlings give high pitched calls from within the egg, and from hatching until they are about 7 days old. These are probably begging calls or perhaps expressing discomfort. The vocal pitch changes at about 7 days and becomes lower. Adults sometimes direct calls at human territorial intruders. Both males and females bark, scream, whine, and give broken wing distraction displays to defend the nest and young from potential threats. In late February and March, territorial songs are sung. (Holt and Leasure, 1993)

Short-eared owls have keen vision, especially in low light. They also use their excellent sense of hearing to help locate and capture prey.

Short-eared owls prey primarily on voles, mice, and other small mammals. Their strong talons and sharp beak make them well adapted to 'picking up' their food while in flight. These owls may utilize a 'perch-and-pounce' hunting method if there is an adequate perching point available. Otherwise, they hunt by flying two meters above the ground in a regular, slow manner. Short-eared owls rely mainly on auditory clues; using these alone, they can catch prey that is under continuous grass cover. (Martin, 1990 and Pearson, 1936)

Short-eared owls are vulnerable primarily to mammalian predation due to the type of open habitat they occupy and their ground nesting habit. Short-eared owls fly fast and directly at an intruder, pulling up and presenting their talons at the last moment. They often use thermal updrafts during skirmishes and rise vertically, chasing and interacting with intruders. They may scream, whine, and distract predators on eggs or nestlings by pretending to have a broken wing.

Short-eared owls are important predators on populations of many different types of small mammals and birds.

There are no known negative effects of short-eared owls on humans.

Short-eared owls help manage animals that humans consider to be pests; a large portion of their diet is small rodents, such as mice and voles. In areas where small mammals can reach plague numbers, short-eared owls capitalize on the opportunity and settle in large numbers. (Sparks and Soper, 1989 and Pearson, 1936)

Due to their wide distribution, short-eared owls are not a federally endangered species; however, in the Great Lakes region of the United States, conditions are worse. This species is threatened by the diminishing area of marshes, bogs, and open grasslands. Nesting habits and nomadism make this species particularly vulnerable to habitat loss during any season. Due to these factors, short-eared owls are endangered in Michigan, Illinois, and Pennsylvania. They are also threatened in Minnesota and of special concern in Indiana and Ohio. They are among the rarest nesting owls in Michigan. There are no major efforts to help them recover in these areas. (Granlund et al., 1994)