Short Eared Owl

More info for the terms: forest, taiga, tundra

The short-eared owl occurs in most open plant communities in North
America [12,13,21,22,28]. Taiga is usually used only in late summer
[12]. The owl avoids tundra and closed-canopy brushland and forest
[12,21,22,32].

short-eared owl

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United States and Canada is available at NatureServe, although recent
changes in status may not be included.

More info for the term: cover

Nesting cover - Short-eared owl require open areas with dense, tall
herbs for nesting. They are the only North American owl that habitually
build their own nest each year. Nesting short-eared owl build the nest
with sticks and rotting vegetation; they approach it through a short
tunnel in the thick grass [28]. Duebbert and Lokemoen [15] found that
in North Dakota rangeland planted to smooth brome (Bromus inermis),
intermediate wheatgrass (Thinopyrum intermedium), and tall wheatgrass
(Elytrigia elongata), owls selected sites where grass cover was 12 to 24
inches (30-60 cm) tall. Seventy-five percent of nests were
three-fourths concealed from the sides; tops were mostly open. Evrard
and others [18] found that in a Wisconsin old field, nesting cover was
mostly 3-foot (90-cm) quackgrass (Elytrigia repens).

Hunting cover - Short-eared owl require open landscapes for hunting.
They generally hunt on the wing, flying low [28], but occasionally hunt
from low perches such as saplings and fenceposts [7].

Roosting cover - Short-eared owl usually roost on the ground or on grass
tussocks, although they occasionally use low brush [28], fenceposts, and
telephone poles [9]. During winter in snow country, they often roost
communally in low-growing conifers [12,28,33,39]. Observers in New
Jersey saw short-eared owl flocking together and roosting in short
conifers whenever snow cover was greater than 30 inches (75 cm) [9].

The short-eared owl occurs on all continents except Australia and
Antarctica [5,12,28]. In North America, it is distributed from Alaska
and all Canadian provinces except the Northwest Territories south
through the conterminous United States to central Mexico. It also
occurs on Pacific and Caribbean islands including Hawaii, Puerto Rico,
and the Virgin Islands [12,22,23,28].

Unlike most owls, short-eared owl hunt both day and at night until
sufficient prey are taken [12,28]. Throughout most of North America,
the meadow vole (Microtus pennsylvanicus) is selectively hunted and
comprises at least 90 percent of the short-eared owl's diet
[5,12,14,26,28]. Clark [12] speculated that on this continent,
short-eared owl cannot reproduce unless sufficient meadow vole are
taken. Current knowledge of short-eared owl food habits and nutritional
requirements is insufficient to determine whether this is true, however
[50]. Minor items in the short-eared owl diet include other voles
(Microtus spp.), deer mouse (Peromyscus maniculatus), shrews
(Soricidae), and small birds [9,46,48]. In Hawaii, the house mouse (Mus
musculus) and the Polynesian rat (Rattus exulans) are primary prey
[22,42].

More info for the terms: fire suppression, succession

Fire was historically an important disturbance in many of the plant
communities short-eared owl occupy. It created grass patches within
shrublands, maintained the open structure of parklands, and prevented
woody plant invasion of marshlands and grasslands. Although much of
short-eared owl decline can be attributed to urbanization, at least some
is probably due to succession of open plant communities to closed ones
as a result of fire suppression. Expansion of eastern deciduous species
into prairie, for example, has reduced short-eared owl habitat [32].

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

13 Black spruce - tamarack
37 Northern white-cedar
38 Tamarack
68 Mesquite
209 Bristlecone pine
242 Mesquite
250 Blue oak - Digger pine

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

FRES26 Lodgepole pine
FRES28 Western hardwoods
FRES29 Sagebrush
FRES30 Desert shrub
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
FRES41 Wet grasslands
FRES42 Annual grasslands
FRES44 Alpine

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the terms: cactus, forest, shrub

K022 Great Basin pine forest
K030 California oakwoods
K042 Creosotebush - bursage
K043 Paloverde - cactus shrub
K048 California steppe
K049 Tule marshes
K051 Wheatgrass - bluegrass
K052 Alpine meadows and barren
K053 Grama - galleta steppe
K054 Grama - tobosa prairie
K055 Sagebrush steppe
K056 Wheatgrass - needlegrass shrubsteppe
K057 Galleta - three-awn shrubsteppe
K058 Grama - tobosa shrubsteppe
K061 Mesquite - acacia savanna
K063 Foothills prairie
K064 Grama - needlegrass - wheatgrass
K065 Grama - buffalograss
K066 Wheatgrass - needlegrass
K073 Northern cordgrass prairie
K074 Bluestem prairie
K077 Bluestem - sacahuista prairie
K079 Palmetto prairie
K080 Marl - everglades
K088 Fayette prairie
K092 Everglades
K093 Great Lakes spruce - fir forest
K094 Conifer bog

More info for the term: cover

Short-eared owl populations have declined over most of their former
North American range due to habitat loss [24]. By 1986, they were
widely reported as declining in the Hudson-Delaware region, the Midwest,
and the Southern Great Plains; in severe decline in central-southern,
prairie, and mid-Pacific coast regions; and long since extirpated from
southern California [17]. In the Midwest, short-eared owl are currently
reported only from remnant prairie [44]. Baldner [2] and Sinclair [43]
attributed the species' rarity in Iowa to loss of tallgrass prairie.
Urbanization of coastlands has decimated populations in Massachusetts
[12,45]. Central California populations have been reduced by
agricultural and urban development [21]. Marti and Marks [35] have
listed populations as stable in Oregon and Colorado and fluctuating but
stable in Montana.

Short-eared owl often persist near farmland borders where agriculture is
not intensive. Intensive agriculture or conversion of meadows,
wetlands, or other short-eared owl habitat to cropland, however, results
in short-eared owl decline [24,29].

Overgrazing removes cover needed for nesting and brooding [21,35]. In
Idaho, short-eared owl were present in ungrazed big sagebrush-standard
wheatgrass (Artemisia tridentata-Agropyron desertorum), but not in areas
grazed by sheep [40,41].

AL
AK
AZ
AR
CA
CO
CT
DE
FL
GA

HI
ID
IL
IN
IA
KS
KY
LA
ME
MD

MA
MI
MN
MS
MO
MT
NE
NV
NH
NJ

NM
NY
NC
ND
OH
OK
OR
PA
RI
SC

SD
TN
TX
UT
VT
VA
WA
WV
WI
WY

DC
PR
VI


AB
BC
MB
NB
NF
NS
ON
PE
PQ

SK
YT

MEXICO

Large avian predators such as great horned owl (Bubo virginianus) [4],
snowy owl (Nyctea scandiaca) [33], and rough-legged hawk (Buteo lagopus)
[36] occasionally prey upon both juvenile and adult short-eared owl.
Ground-nest predators such as American badger (Taxidea taxus) [47] and
gulls (Larus spp.) [12] eat the eggs.

More info for the terms: cover, heath, herbaceous, marsh, taiga, tundra

Short-eared owl occupy a variety of open habitats within their wide
geographical distribution. Preferred habitats include fresh- and
saltwater marshes [6,7,12,21], coastal plains [24], tamarack (Larix
laricina)-black spruce (Picea mariana) bogs [8], old fields [14,18],
prairies [30], sagebrush (Artemisia spp.) steppes [38,40,42], wet
meadows, grasslands, open shrublands, and montane parklands [21,22].

Since the species is only weakly migratory, nesting, hunting, and
wintering habitats are generally the same [12,28]. In Massachusetts,
short-eared owl in maritime heath occupied a home range of 63 to 198
acres (25-79 ha) [45]. In freshwater marsh, the home range was 184.8 to
303.5 acres (73.9-121.4 ha) [12].

Nesting habitat - Short-eared owl nest on dry ground in open areas with
dense herbaceous cover. Even in wetlands, dry microsites are selected
for nesting [13]. Taiga and tundra are poor nesting habitat [12].

Hunting habitat - The owl uses open ground where prey is available [7,33].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

The currently accepted scientific name of short-eared owl is Asio
flammeus (Pontoppidan) [1]. It is in the family Strigidae [28]. Only
the type subspecies, Asio flammeus flammeus, occurs in North America.
A. f. ponapensis, Ponape short-eared owl, occurs on the Caroline
islands, and A. c. sandwichensis, Hawaiian short-eared owl, occurs on
the Hawaiian islands [13,28].

More info for the terms: heath, marsh, taiga

Age at sexual maturity - 1 year [27]

Courtship and breeding - Short-eared owl form pair bonds; whether the
pairing lasts past the breeding season is unknown [27]. Depending upon
latitude, courtship begins in mid-winter or early spring, and breeding
is completed by late winter or late spring. In Idaho and Massachusetts,
courtship begins in March and the female lays eggs by May [2,24]. In
Illinois, courtship begins in late April and egg-laying is complete by
early May [28].

Nesting and incubation - Most North American populations are
single-brooded, although short-eared owls in the South are sometimes
double-brooded. Clutch size varies from 2 to 14 eggs, with 5 to 7 eggs
being the norm [28]. The female tends to lay more eggs when prey
populations are high [13]. Murray [37] found that clutch sizes were
significantly larger with increasing latitude; he attributed this to
larger rodent populations in the North. The female lays her eggs
asynchronously, from 2 to 7 days apart. Regional egg-laying dates are
given below [28].

Alaska and arctic Canada: June 5-July 2; usually June 10-June 25
southern Canada: April 30-June 22; usually May 4-June 17
northern United States: April 14-June 15; usually April 23-June 10
Midwest: April 4-June 8; usually April 16-May 25
southern California: March 20-May 18; usually March 26-April 26

Destroyed clutches are usually replaced within 2 weeks; second clutch
sizes are smaller [12,28].

The female is the sole incubator; the male supplies her with food during
incubation. Incubation time is 21 to 29 days per egg. The eggs hatch
asynchronously, about one every 3 days. The brood therefore consists of
different-aged sibs. The female does all brooding; the male hunts to
feed the young and his mate [12,16,24,28].

Fledging - Young leave the nest on foot about 16 days after hatching and
fledge at approximately 29 days of age [24,25]. The brood is dependent
on the parents for food "for a period of time" after fledging [13].
After all young have fledged, parents lead the brood to a new area if
prey is scarce on the nesting grounds [34].

Clark [12] reported a mean clutch size of 8.6 for short-eared owl nests
in a Massachusetts freshwater marsh. An average of 7.0 young per nest
hatched, and an average of 4.0 young per nest fledged. On Nantucket
maritime heath, Tate and others [45] found a mean clutch size of 5.7 in
1985. An average of 3.4 eggs hatched, and 2.0 young per nest fledged. In
1986, mean clutch size was 7.7, with an average of 7.0 eggs hatching and
3.4 young per nest fledging.

Migration - Much remains to be discovered about short-eared owl
migration dates and routes. The short-eared owl is well adapted to heat
and cold. As a result, it is apparently only weakly migratory [28].
Short-eared owl populations at the edge of the species' northern
distribution move south in late summer or early fall, but it is unclear
whether more southerly populations migrate or remain in an area as
permanent residents. Banding records are few, but limited studies show
that some individuals in populations south of taiga are regular
migrants. Others are irregular migrants, leaving in some years but not
others. Some owls probably migrate to new areas as young adults, then
become permanent residents. Migration routes are generally north-south,
but not always. Some migrants, for example, move back and forth from
North Dakota and eastern Oregon [12].

Except for populations at climatic extremes, when entire populations
migrate it is usually in response to depletion of the prey base rather
than seasonal climate changes. Short-eared owl rapidly move out of an
area bereft of prey, and rapidly move into areas where rodent
populations are rising [12,29,34].

Longevity - Captive birds have lived to age 15. It is unknown how long
short-eared owl usually survive in the wild [28].

More info for the terms: cover, fire regime

Fire can maintain or expand short-eared owl habitat. Burning after the
fledging stage, so that young owls are not lost to fire, is probably
best [30]. Because summer or fall fires are usually more severe than
spring fires, they would probably kill more woody vegetation, opening up
habitat as well as avoiding damage to reproduction. Burning during the
nesting season, however, does not totally eliminate reproduction of
ground-nesting birds such as short-eared owl. Kruse and Piehl [30]
recommended partial burning during the nesting season. Partial burns
reduce cover less uniformly, but should result in higher recruitment of
ground-nesting birds than would complete burns conducted during the
nesting season.

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".