Dall's Sheep in Alaska
Articles and Links for Dall’s Sheep Monitoring
- Press Release: New Approach to Dalls Sheep Monitoring Better, Cheaper
- Article: Reducing Effort While Improving Inference: Estimateing Dall’s Sheep Abundance and Composition in Small Areas (2013)
- Article: Using Distance Sampling and Hierarchical Models to Improve Estimates of Dall’s Sheep Abundance (2012)
- Videos: Dall’s Sheep Monitoring in Alaska
- Flickr Photos: Dall’s Sheep Monitoring
- Link: Dall’s Sheep Monitoring in Arctic parks
- Link: Dall’s Sheep monitoring in Central Alaska parks
- Link: Sheep in the Arctic Refuge
- Link: Sheep Info from the State of Alaska
Dall’s sheep in National Parks
Approximately 40% of the world's population of Dall's sheep are found in national park units in Alaska. These agile herbivores navigate the steep slopes of mountain ranges across the state to escape predators. The National Park Service monitors the abundance and composition (age and sex ratios) of this species. Dall’s sheep are a popular harvested species, which makes having accurate population estimates important for the sustainable long-term management of the species and its allowable harvest.
New Approaches Lead to Better Results
Scientists with the National Park Service in Alaska have recently applied distance sampling techniques to sheep surveys in Alaska parks. The result of their efforts is the first rigorous landscape-scale estimates of sheep populations in these areas in several decades. The newly applied methods require 70-80% less effort than standard approaches and greatly increase survey completion rates across large areas.
The approach was first developed and implemented in Gates of the Arctic National Park and Preserve during 2009 and 2010 where comprehensive surveys were completed for the first time in nearly 30 years. In 2011 and 2012, they extended these methods to increase their applicability in smaller areas or places with relatively few sheep, while also providing estimates of population composition (e.g., lambs, ewes, etc.).Areas surveyed include Noatak, Kobuk Valley, Cape Krusenstern, Denali, Wrangell-St. Elias, and Lake Clark.
Based on the 2010-2012 surveys, the esitmated population of Dall’s sheep in national park units of Alaska is 26,000 to 28,000 individuals.