This paper, published in Airo, presents results from monitoring in North and South America. Click here to view PDF.
Gahbauer, M. A., R. A. Miller, N. Paprocki, A. Morici, A. C. Smith, and D. A. Wiggins. 2021. Status and monitoring of Short-eared Owls (Asio flammeus) in North and South America. Proceedings of the 2017 World Owl Conference. Évora, Portugal. Airo 29:115–142.
The breeding range of the Short-eared Owl (Asio flammeus) in North America includes all 13 Canadian provinces and territories, and approximately 25 states in the United States; the wintering range extends south to northern Mexico. It is listed as a species of Special Concern in Canada under the Species at Risk Act and subject to special protection in Mexico, but is not covered under the United States Endangered Species Act, although NatureServe has ranked the species as imperiled or critically imperiled in 21 states. In South America, it is found in eight countries, and is considered vulnerable in Argentina. Its conservation status is highly influenced by assessment of population trends, which are derived from multiple sources, each of which has advantages and limitations. In North America, both the Breeding Bird Survey and Christmas Bird Count reveal a widespread decline over the past half century, especially in the midwest and northeast United States. Several second-generation state and provincial breeding bird atlases have shown a reduction in the occurrence of Short-eared Owls compared to initial results approximately 20 years earlier. Overall though, traditional multi-species monitoring programs have not been effective at assessing Short-eared Owl populations. The Western Asio flammeus Landscape Study (WAfLS) is the first regional monitoring effort specific to this species, using standardized surveys and modeling the results using occupancy analysis. Over its first three years, it has already yielded valuable data on population fluctuations, and the WAfLS approach can be readily adapted to other regions. In South America, monitoring to date has been more limited and further research is required, but it is thought there have also been widespread declines related to habitat loss.