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.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
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)
US Migratory Bird Act: protected
US Federal List: no special status
CITES: appendix ii
State of Michigan List: endangered
IUCN Red List of Threatened Species: least concern
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)
Positive Impacts: controls pest population
Short-eared owls are important predators on populations of many different types of small mammals and birds.
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)
Animal Foods: birds; mammals
Primary Diet: carnivore (Eats terrestrial vertebrates)
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)
Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native )
Other Geographic Terms: cosmopolitan
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)
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Wetlands: marsh ; swamp ; bog
Other Habitat Features: agricultural
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.
Range lifespan
Status: wild: 21.8 (high) years.
Average lifespan
Status: wild: 53 months.
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)
Range mass: 206 to 475 g.
Average mass: 347 g.
Range length: 340 to 423 mm.
Range wingspan: 950 to 1100 mm.
Average basal metabolic rate: 313.375 cm3.O2/g/hr.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
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.
Known Predators:
The difficulty of owl reproduction lies in their usually individualistic habits; a great amount of the effort goes into learning mutual recognition as mating partners rather than prey or predator. They even have some difficulty identifying the gender of prospective mates from a distance. Male short-eared owls use an aerial display that includes wing clapping to alert the female of his presence and sex. Males also may offer food to females; this prevents females from considering the male as food.
Pair formation begins in mid-February and continues through June. Breeding usually begins in April. Short-eared owls are reported to also raise a second brood although this is not confirmed. To attract females, males perform sky dancing displays, day or night. The sky dance consists of song accompanied by aerial acrobatics. Short-eared owls are generally thought to be monogamous; however, the pair bond probably does not last beyond the breeding season. (Holt and Leasure, 1993)
Mating System: monogamous
After sufficient time and caution has been taken, the male mounts the female. One observer reported that copulation took 4 seconds, after which the male and female flew in different directions. Breeding usually takes place while in their summer habitat, but they may breed in their wintering area if food is plentiful. Short-eared owls nest on the ground in protection provided by tall grasses; they often return to the same nests. Each nest contains 4 to 7 white, unspotted eggs. The eggs have an average incubation of 21 days. Nestlings have been known to prey on their smaller nest mates. The young usually disperse from the nest when they are about 14 to 17 days old. They are independent 1 to 2 weeks after fledging. (Holt and Leasure, 1993; Sparks and Soper, 1989; Pearson, 1936; Welty, 1975)
Breeding interval: Short-eared owls typically breed once yearly in the spring. Second broods have been reported but data is still needed to confirm this.
Breeding season: Short-eared owls typically breed late March to June, but mostly in April. In the southern hemisphere, breeding begins in September.
Range eggs per season: 1 to 11.
Average eggs per season: 5.6.
Range time to hatching: 21 to 37 days.
Range fledging age: 24 to 36 days.
Range time to independence: 31 to 43 minutes.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Average eggs per season: 6.
Average age at sexual or reproductive maturity (male)
Sex: male: 365 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 365 days.
Only females brood and feed nestlings, while male provide food and defend the nest with distraction displays and vocalizations. Females protect nestlings from some weather conditions by brooding when young, and mantling when larger. When they are born young are semi-altricial, which means that they are relatively immobile and helpless when they hatch, but are down-covered rather than naked. (Holt and Leasure, 1993)
Parental Investment: altricial ; male parental care ; female parental care
