2008 aerial Dall’s sheep survey in the Itkillik Preserve, Gates of the Arctic National Park and Preserve, Alaska
Dates
Year
2010
Citation
Rattenbury, Kumi L., and Lawler, James P., 2010, 2008 aerial Dall’s sheep survey in the Itkillik Preserve, Gates of the Arctic National Park and Preserve, Alaska: National Park Service Natural Resource Program Center National Park Service: National Park Service, Fort Collins, Colorado, v. NPS/ARCN/NRTR—2010/409.
Summary
This report summarizes methods and results for an aerial Dall’s sheep (Ovis dalli dalli) survey conducted in 2008 by the National Park Service Arctic Network Inventory and Monitoring Program, with support from the Alaska Department of Fish and Game, in the northeastern portion of Gates of the Arctic National Park and Preserve, Alaska. This area includes the Itkillik Preserve, where the highest densities of Dall’s sheep in the Park and Preserve have been found, and both subsistence and sport hunting are allowed. Approximately 1905 km2 of delineated habitat were surveyed via small, fixed-wing aircraft from 9-14 July. Sheep groups were counted and classified as lambs, ewe-like sheep (ewes, yearlings and rams with less than ½ curl horns), [...]
Summary
This report summarizes methods and results for an aerial Dall’s sheep (Ovis dalli dalli) survey conducted in 2008 by the National Park Service Arctic Network Inventory and Monitoring Program, with support from the Alaska Department of Fish and Game, in the northeastern portion of Gates of the Arctic National Park and Preserve, Alaska. This area includes the Itkillik Preserve, where the highest densities of Dall’s sheep in the Park and Preserve have been found, and both subsistence and sport hunting are allowed. Approximately 1905 km2 of delineated habitat were surveyed via small, fixed-wing aircraft from 9-14 July. Sheep groups were counted and classified as lambs, ewe-like sheep (ewes, yearlings and rams with less than ½ curl horns), sub-curl rams (= ½ curl and < full-curl) and = full curl rams. We observed 315 groups of Dall’s sheep, totaling 1239 individuals (961 adults, 276 lambs, and two sheep that could not be classified). There were 40 lambs per 100 ewe-like sheep, 41 rams per 100 ewe-like sheep, and 19% of the rams were full-curl. Overall density of observed sheep was 0.65 sheep/km2. These are unadjusted count and composition data collected for the Arctic Network’s monitoring program with the objective of detecting trends in the abundance and distribution of Dall’s sheep in the central and western Brooks Range. The 2008 data, as well as data from a more extensive survey conducted in 2005, indicate a healthy and productive sheep population that has likely increased since a regional decline observed in the early 1990s, albeit not to the numbers counted in the same area in the early 1980s. Recommendations for future survey work are discussed.
