Asio flammeus - continental North America

This species is complete.

January 31, 2012 by Diane Evans-Mack

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Sensitivity Factor	Sensitivity Help 1 - 7 (one being least sensitive, seven being most sensitive)	Confidence Help 1 - 5 (one being least sensitive, five being most sensitive)
Generalist/Specialist	4 Medium-High	4 Good
Physiology	1 Low	4 Good
Life History	5 High	5 Very Good
Habitat	7 Extremely High	4 Good
Dispersal Ability	1 Low	4 Good
Disturbance Regimes	5 High	3 Fair
Ecology	4 Medium-High	4 Good
Non-Climatic	3 Medium	3 Fair
Other (weight)		3 Fair

Sensitivity Score Help: 53 Medium

Sensitivity Score

100 * [(0.5 *(Dispersal Distance + Dispersal Barriers) + Disturbance Regimes + (0.5 * Generalist/Specialist) + Physiology + (0.5 * Life History) + Sensitive Habitats + Ecology + Non-Climatic Stressors + (Other * Weight) / 49 + (7 * Weight)]

Note: if Sensitive Habitats are identified, this factor automatically gets a value of seven, otherwise it remains zero.

Confidence Score Help: 3 Fair

Confidence Score

The Confidence Score is an average of the Confidence column above.

Overall User Ranking: 2 Medium-Low

Common Name:

short-eared owl

Is this Species completed:

Yes

Taxonomy

This is a description of the whole group

Scientific Name:

Asio flammeus

Geography:

continental North America

Realm:

Terrestrial

Kingdom:

Animal

Class:

Aves

Order:

Strigiformes

Family:

Strigidae

Genus:

Asio

Global Rank:

G5 (2005)

Rounded Global Rank:

G5- Secure

Target Rationale:

Declining

Generalist/Specialist

Broadly, where does this species fall on the spectrum of generalist to specialist? :

Confidence in your assessment of the degree to which the species is a generalist or specialist:

4 Good

Please specify which factors, if any, make the species more of a specialist:

predator/prey relationship

Please further describe the relationships that make the species more of a specialist:

Microtus voles are a primary prey species; variation in short-eared owl population size attributed to variation in small mammal abundance

Comments:

Large, annual fluctuations in breeding Short-eared Owls was tightly correlated with the abundance of small mammals in a study on the Alaskan tundra.

Citations:

Johnsgard 1988 -- full cite above under dispersal ability Wiggins et al 2006 -- full cite above

Physiology

Species' physiological sensitivity:

1 low sensitivity

Confidence in how physiologically sensitive the species is to climate change:

4 Good

Please describe any specific physiological sensitivities:

No physiological sensitivities mentioned in the limited literature I have at my disposal.

Comments:

Although mostly a bird of northern latitudes, which might suggest a sensitivity to temperature, some individuals winter across the lower 48 states and it has been documented nesting in Cuba (different sub species?). Thus, temperature doesn't seem to be a limiting factor.

Life History

Species' reproductive strategy:

Confidence in your assessment of the species' reprodcutive strategy:

5 Very Good

Is the species polycyclic, iteroparous, or semelparous?:

Iteroparous (reproduces in successive cycles--characteristic of K-strategists)

Average length of time to reproductive maturity:

340 days

How many surviving young can an individual produce during a single reproductive event under optimal conditions?:

2-5

How many reproductive events can an individual undergo in a single year under optimal conditions?:

Comments:

Sexually mature in first year after fledging. Clutch size varies, but averages 5.6 in North America. Hatching success 3-7 yg. Reproductive sucess can be low (<2 yg fledged per nest) due to nest and chick vulnerability in agricultural landscapes. Avg 2-5 yg fledged/nest across northern range.

Citations:

Johnsgard 1988. Full cite above. Wiggins et al 2006. Full cite above.

Sensitive Habitats

Depends on the following sensitive habitat types:

Coastal Lowlands/Marshes/Estuaries/Beaches

Grasslands/balds

Confidence in whether the species depends on the listed sensitive habitat types:

4 Good

Level of philopatry:

low

Comments:

occurs in inland or coastal marshes, but not sure it 'depends' on this habitat. Philopatry overall is low. Fidelity to breeding areas variable across range. Some breeding territories were similar over 2 successive years. 4 of 28 adults returned to same breeding sites in Scotland; 0 of 28 females recaptured in Montana. Nomadic behavior lends itself to lower philopatry.

Citations:

Wiggins et al 2006. Full cite above.

Dispersal Ability

Maximum annual dispersal distance:

>100 km

Confidence in maximum annual dispersal distance:

5 Very Good

Within the context of dispersal distance above, do barriers to dispersal exist?:

Confidence in barriers to dispersal exists:

4 Good

Specific dispersal distance (if known), and dispersal type (juvenile, adult, etc.):

1730 km for an adult moving south in fall; distances up to 2000 km for juvenile dispersers

Please select the types of barriers relevant to dispersal:

Industrial or Urban Development

Suburban or Rural Residential Development

Comments:

Colonization of /presence on islands suggests an ability to colonize new areas, even over water, at a distance ≥ 145 km

Citations:

Wiggins, D. A., D. W. Holt and S. M. Leasure. 2006. Short-eared Owl (Asio flammeus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/062 Johnsgard, P. A. 1988. North American owls - biology and natural history. Smithsonian Institution Press, Washington, DC.

Disturbance Regimes

How sensitive is this species to one or more disturbance regimes:

5 more sensitive

Confidence in how sensitive is this species on one or more disturbance regimes:

3 Fair

Please check all disturbance regimes upon which the species is sensitive:

Flooding

Urbanization

Please describe the disturbance regimes upon which the species is sensitive (frequency, timing, severity, duration):

flooding during nesting season; urbanization that results in habitat loss affects the species year-round

Comments:

Nesting habits and nomadism make this species particularly vulnerable to habitat loss at any season. Conversion of open habitats to agriculture, grazing, recreation, housing, and resort development a key factor in declines.

Citations:

Ecological Relationships

Please specify which of the following (if any) are sensitive to climate change for this species:

predator/prey relationship

habitat

Confidence in how sensitive the species is to other effects of climate change on its ecology:

4 Good

Which types of climate and climate-driven changes in the environment affect these aspects of the species' ecology?:

temperature

precipitation

How sensitive is this species’ ecological relationships to the effects of climate change?:

Interacting non-climatic stressors

To what degree do other, non-climate-related threats, to the species make it more sensitive to climate change?:

Confidence in the degree to which non-climate-related threats affect the species' sensitivity to climate change:

3 Fair

Comments:

Conversion of habitats to agriculture or urbanization affects population health; fragmentation of habitats that reduces area and creates more edge increases risk to predators; timing of agricultural practices (mowing, harvesting) can result in substantial nest loss, decreasing productivity

Citations:

Wiggins et al 2006.

Other Sensitivities

Are there other critical factors that have not been addressed, which may make this species more sensitive to climate change?:

Can't think of any.

Confidence in other critical factors:

3 Fair

Confidence in the degree to which these factors make this species sensitive to climate change:

3 Fair

Overall User Ranking

In your opinion, how would you rank the overall sensitivity of this species to climate change?:

Confidence in your overall assessment of the sensitivity of this species to climate change:

4 Good

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Climate Change Sensitivity Database

Asio flammeus - continental North America

Sensitivity Score

Confidence Score