Short-eared Owl 2019 Annual Report
In 2019 the expanded WAfLS project continued into its second year. A large group of volunteers sampled survey grids across eight western stated. The 2019 abundance estimates and habitat associations results add even more insight to land managers across the western United States to influence species-specific general conservation actions. CLICK HERE TO VIEW PDF.
2019 Western Asio flammeus Landscape Study (WAfLS) Annual Report Version 1.0
Robert A. Miller (a,1),Carie Battistone (b), Heather Hayes (a), Matt D. Larson (c), Joseph G. Barnes (d), Ellie Armstrong (e), Annette Hansen (f), Nelson Holmes (f), Joseph B. Buchanan (g), Zoë Nelson (h), Jay D. Carlisle (a), and Colleen Moulton (i)
a – Intermountain Bird Observatory, Boise, Idaho, USA;
b – California Department of Fish and Wildlife, Sacramento, California, USA;
c – Owl Research Institute, Missoula, Montana, USA;
d – Nevada Department of Wildlife, Las Vegas, Nevada, USA;
e – Klamath Bird Observatory, Medford, Oregon USA;
f – HawkWatch International, Salt Lake City, Utah, USA;
g – Washington Department of Fish and Wildlife, Olympia, Washington, USA;
h – Biodiversity Institute, Laramie, Wyoming, USA;
i – Idaho Department of Fish and Game, Boise, Idaho, USA
1 – Correspending author: RobertMiller7@boisestate.edu; 208-860-4944
The Short-eared Owl (Asio flammeus) is an open-country species that breeds in the northern United States and Canada, and has likely experienced a long-term, range-wide population decline. However, the cause and magnitude of the decline are not well understood. Following Booms et al. (2014), who proposed six conservation actions for this pecies, we set forth to address four of these objectives within the Western Asio flammeus Landscape Study (WAfLS) program: 1) better define and protect important habitats; 2) improve population monitoring; 3) better understand regional owl movements; and 4) develop management plans and tools. Population monitoring of Short-eared Owls is complicated by the fact that the species is an irruptive breeder with low site fidelity, resulting in large shifts in local breeding densities, often tied to fluctuations in prey density. It is therefore critical to implement monitoring at a scale needed to detect regional changes in distribution that likely occur annually. We recruited 605 participants, many of which were community-scientist volunteers, to survey at study sites embedded over 87 million hectares within the states of California, Idaho, Montana, Nevada, Oregon, Utah, Washington, and Wyoming during the 2019 breeding season. We surveyed 334 transects, 273 of which were surveyed twice, and detected Short-eared Owls on 57 transects. We performed multi-scale occupancy modeling and maximum entropy modeling to identify population status, habitat and climate associations. Our estimated occupancy rates suggest an annual increase in breeding density in the northern and eastern states, most strongly in Montana, followed by Washington, Wyoming, and Utah. Idaho, Nevada, Oregon, and California had lower breeding densities than in 2018. These numbers will help us to put future changes into perspective. We most often found Short-eared Owls at points with complex grassland, fallow agriculture fields, and with lower levels of grazing. In contrast to 2018, this year shrubland landscapes were not favored, likely influenced by the shift in breeding density toward eastern Montana. Transect occupancy was most strongly associated with grasslands, hay, and fallow fields, with orchards and vine crops specifically avoided. Our results continue to find that Short-eared Owls have a climate association that puts them at great future risk, primarily their apparent preference of landscapes with higher relative precipitation and moderate seasonality. As our summers continue to become drier, as is expected under most climate scenarios, we expect a further decrease in the population of this species, possibly through the climate’s effect on prey abundance. Our results demonstrate the feasibility, efficiency, and effectiveness of utilizing public participation in scientific research (i.e., community scientists) to achieve a robust sampling methodology across the broad geography of the western United States. We look forward to the continued implementation of this program in future years and directly influencing conservation actions.
Key Words: community-science | conservation | habitat use | occupancy | population trend | Short-eared Owl