Item: A COMPLEX RELATIONSHIP: SIERRA NEVADA BIGHORN SHEEP AND SNOW
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Title: A COMPLEX RELATIONSHIP: SIERRA NEVADA BIGHORN SHEEP AND SNOW
Proceedings: International Snow Science Workshop 2024, Tromsø, Norway
Authors:
- Edward Bair [ Leidos, Inc. ]
- Karl Rittger [ University of Colorado ]
- Tom Stephenson [ California Department of Fish and Wildlife ]
- Danielle Berger [ Utah State University ]
- Kezia Manlove [ Utah State University ]
- Huilin Huang [ Pacific Northwest National Laboratory ]
- Yun Qian [ Pacific Northwest National Laboratory ]
- Carrie Vuyovich [ National Aeronautics and Space Administration ]
Date: 2024-09-23
Abstract: Sierra Nevada bighorn sheep are an endangered species who inhabit avalanche-prone areas of the central and southern parts of the range. Due to severe winters, disease, and predation, the animals almost became extinct with only 100 individuals left in 1995. Through conservation efforts, including those of the California Department of Fish and Wildlife's Bighorn Sheep Recovery Program, the population grew to 600 in 2015, but record snow in 2023, combined with increased mountain lion predation, have reduced the current population to 350. The sheep have a complex relationship with snow, as it is the main source of water for their forage, yet 73 dead sheep have been found in avalanche debris over the past 14 years, with up 12 deaths from a single avalanche. To better understand how the sheep interact with snow and avalanches, simulations were run for our current (1990-2020) and future (2050-2080) climate under a pseudo warming scenario, a downscaling method for coarse spatial resolution climate projections. For the current climate, daily timespace cubes of avalanche hazard covering the past 20 years across the range were built. The cubes use hazard forecasts from the Sierra Avalanche Center, snow depth, as well as terrain slope and canopy cover. Snow depth estimates are from 2 km Weather Research Forecast model output. Current climate avalanche hazard was then applied to the diminished snowpack under warming to estimate future avalanche hazard. Results suggest that avalanches will continue to cause fatalities for the bighorn sheep in a warmer climate and, if the number of extremely wet events increases as predicted, avalanche fatality rates may increase.
Object ID: ISSW2024_P5.10.pdf
Language of Article: English
Presenter(s): Edward Bair
Keywords: avalanche, snow, sheep, climate change, remote sensing
Page Number(s): 682 - 685
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