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, Barn Owl, and
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. Records indicate that they have never been
common breeders in Colorado (Boyle 1998).
Habitat Requirements: These owls breed and forage in grasslands, prairies, wetlands, and
croplands. Large blocks of suitable habitat (100 ha; 250 ac) seem necessary to support breeding
pairs. The birds nest on the ground, usually on a dry site, often elevated on a small hummock.
Ecology: They lay eggs 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 of land to uses such as urbanization that are
incompatible with the owls' nesting and foraging. Conservation efforts should focus on
landscapes of prairie with suitable habitat for Short-eared Owls. Current breeding sites can be
used as one layer of information in selecting these sites; however, any single effort appears
likely to have a relatively small impact if current population and distribution records are
accurate. Assure that large areas of habitat are available for the species. This approach may
be most successful in North Park and the San Luis Valley.
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. The Short-eared Owl is not adequately monitored by the
BBS within Physiographic Area 36, and the data 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 measured by results
of MCB and other monitoring programs.
Selected References: Andrews and Righter 1992, Clark 1975, Holt and Leasure 1993, Kingery