Date of Award:

8-2026

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Committee Chair(s)

T.J. Clark-Wolf

Committee

T.J. Clark-Wolf

Committee

Erica Stuber

Committee

Michael Conover

Abstract

Shorebirds have declined worldwide over the past century, mainly due to wetland loss and degradation. Wetlands are sites that are temporarily or permanently flooded and provide critical habitat for shorebirds, especially in arid and semi-arid regions such as the Intermountain West. However, climate change and human water use threaten these wetlands, and how these threats may affect shorebirds in this region remains poorly understood. In the early 1990s, shorebird counts at over 160 wetlands across the Intermountain West provided a broad assessment of shorebird populations in the region. These counts remained the only large-scale surveys until 2022, when the Intermountain West Shorebird Survey was re-established to address data gaps. In this study, I compared shorebird survey data from the early 1990s with new data from 2022 to 2025 to understand how shorebird populations and wetlands have changed across the Intermountain West over the past 30 years. The analysis showed that ~88% of shorebirds in the region relied on only nine wetlands during spring and fall migrations, and seven of these nine sites were saline lakes. Overall, shorebirds declined by 36% in fall and 53% in spring between 1994-1995 and 2022-2025, with more than three-quarters of the 160 evaluated sites holding significantly fewer individuals. Common species, including dowitchers, American Avocets, and Black-necked Stilts, exhibited the steepest declines, averaging 72%, 68%, and 59%, respectively. The extent of surface water in wetlands decreased by ~17% during the same period and was the strongest factor influencing the declines in shorebird numbers. It remained the most important factor in recent years, despite unusually wet and dry years between 2022 and 2025. Shorebird numbers were also higher in wetlands that were closer to other wetlands and when surveys occurred near the peak of shorebird migration. These findings provide a foundation for future research and conservation efforts to benefit shorebirds by recognizing the importance of increasing the extent of surface waters in wetlands and promoting conditions that protect and restore larger, more connected wetland networks across the Intermountain West.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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