Oregons bighorn sheep restoration efforts began with a release of 20 california bighorn sheep (ovis canadensiscalifornian) from british columbia to hart mountain national antelope refuge (HMNAR) in…

The U.S. Fish and Wildlife Service, Region 1, awarded $459,185 to the State of Oregon Department of Fish and Wildlife under the Wildlife Restoration and Basic Hunter Education and Safety program (CFDA 15.611) on January 1, 2026, for a comprehensive bighorn sheep population study at Hart Mountain National Antelope Refuge (HMNAR). This formula grant funds a rigorous research initiative through June 30, 2028, to address a critical decline in Oregon's California bighorn sheep population from over 200 animals in the early 2000s to only 48 by 2020. The study will rigorously estimate summer lamb production, assess over-winter lamb survival rates, identify factors limiting lamb recruitment, and estimate key vital rates for lambs—products essential for developing effective population recovery strategies.

The award supports collaborative monitoring and research activities between the Oregon Department of Fish and Wildlife and U.S. Fish and Wildlife Service refuge staff to address documented discrepancies between summer lamb production estimates and final recruitment figures. The research findings will directly inform the bighorn sheep management plan and environmental impact statement framework, supporting restoration efforts that have historically supplied breeding populations to herds throughout Oregon, Idaho, and Nevada.

Oregons bighorn sheep restoration efforts began with a release of 20 california bighorn sheep (ovis canadensiscalifornian) from british columbia to hart mountain national antelope refuge (HMNAR) in 1954. This population thrived through the early 2000S and served as a source population for restoration of the sub-species throughout most of oregon, as well as herds in idaho and nevada. However, by 2020 the population had declined precipitously and only 48 animals were counted. In 2021, odfw collaborated with USFWS refuge staff on the development of a bighorn sheep management PLAN and environmental impact statement (PLAN). A significant part of this collaboration involves monitoring resident bighorn populations to identify factors impacting herds, and to evaluate results of management actions directed at bighorn populations. Through this monitoring IT has been identified that there are discrepancies between summer lamb production estimates and final recruitment estimates at the end of the biological year. This study will 1) rigorously estimate summer lamb production on HMNAR 2) estimate over-winter lamb survival on HMNAR 3) identify factors limiting lamb recruitment on HMNAR, and 4) estimate key vital rates of lambs for the population