The bighorn sheep near Brownlee are the remnants of the Sheep Mountain herd, which once numbered over 80 individuals following transplants in Oregon by ODFW in the early 1990s. However, following a pneumonia outbreak in 1999, the herd has since dwindled to fewer than 5 individuals. No lambs have been observed since 2009, and repeated testing indicates that chronic infection with bacterial pneumonia is the cause of this group's failure.
The upper end of Hells Canyon represents important bighorn sheep habitat. However, the remaining ewes represent a tiny remnant population with almost no chance of recovery. Furthermore, they represent a threat to other adjacent populations, as wandering bighorns that encounter these sheep may be exposed to the same bacterial pneumonia.
ODFW has proposed to work closely with IDFG to capture and remove the remaining few sheep from the Brownlee area as a prelude to re-establishing a new self-sustaining population.
The two states will work together to capture bighorn sheep using a helicopter. A bighorn sheep disease research facility at South Dakota State University has agreed to accept the sheep following capture.
Following removal, ODFW plans to re-establish the Sheep Mountain herd by transplanting bighorn sheep from the adjacent Lookout Mountain herd. Releases in Oregon could begin as early as next winter if conditions are suitable. The re-establishment of a healthy bighorn sheep herd will ultimately provide better opportunities for bighorn sheep hunting as this population rebuilds.
IDFG would need to complete a legislatively required process prior to considering releasing bighorns on the Idaho side of the river in the future.