Short-eared Owl (Asio flammeus)
Associated Species: Other species that may use habitat in a similar way and/or respond similarly
to threats, management, and conservation activities include Northern Harrier and Western
Distribution: Short-eared Owls are sparsely and widely distributed in Colorado, with more birds
present in winter than in summer. Breeding birds are most common on the plains, with additional
populations in the San Luis Valley and North Park. They are not believed to have ever been
common breeders in Colorado (Boyle 1998).
Habitat Requirements: Short-eared Owls breed and forage in Colorado's grasslands, prairies,
wetlands, and croplands. Breeding pairs require large blocks of suitable habitat (100 ha; 250
ac). Nests are built on the ground, usually on a dry site, often elevated on a small hummock.
Ecology: Eggs are laid in April or May, and young leave the nest by June. Fall migrants arrive in
September-October, and leave in March. Short-eared Owls eat small mammals (especially voles,
Microtus spp.) and occasionally small birds.
Management Issues and Conservation Recommendations: Loss of suitable habitat is the most
pressing issue, with losses coming from conversion to land use types incompatible with this
species' nesting and foraging (such as urbanization). Conservation efforts should focus on
landscapes of prairies with suitable habitat for Short-eared Owls. Current breeding sites can be
used as one layer of information in selecting the sites; however, any single effort appears likely to
have a relatively small impact if current population and distribution records are accurate.
Determining habitat suitability in landscapes identified for conservation initiatives for other
elements of biodiversity (e.g., TNC 1998) may indicate efficiencies. Assure that large areas of
habitat are available for the species.
Habitat management schemes for nesting waterfowl and upland gamebirds generally benefit
Short-eared Owls. Consider the needs of this species when managing for game species.
Populations of the principal prey species (voles) should be maintained at levels compatible with
economic activities on the land.
Status and Reasons for Concern: This species is on the national Watch List, indicating a high
conservation need throughout its range. Short-eared Owls are not adequately monitored by the
BBS within Physiographic Area 62, and data collected between 1966 and 1996 are too sparse to
allow meaningful analysis of trends. This species is monitored by MCB with nocturnal surveys.
Biological Objective: Increase the species' distribution and abundance, as based upon results of
MCB and other monitoring programs.
Selected References: Andrews and Righter 1992, Clark 1975, Holt and Leasure 1993, Kingery