Pneumonia is suspected in a bighorn sheep die-off north of Plains.

This is the second die-off of a wild sheep herd in Montana this year. The other was near Yellowstone National Park, near Gardiner.

Montana Fish Wildlife and Parks personnel saw only 18 sheep during a helicopter survey this month in an area that usually has over 100 sheep. That would be a loss of over 90 bighorn sheep.

More investigation is planned, but disease is the suspected cause, which could be related to "interactions with domestic sheep that occurred on the winter range in 2012 and 2013," according to a FWP news release.

FWP commissioners voted unanimously to close the bighorn sheep hunting district 122 to further protect the herd.