The photo above was taken with a Leica-R 280mm f4 telephoto manual lens, with a 1.4x Extender and an R-to-M adapter, all mounted on a Leica M10-R.
It was such a beautiful day I took off from a Zoom meeting and drove the 50 miles to look for bighorn sheep head butting during the rut. No battles found, just a quiet small group.
One youngster is very hard to see unless you know he is laying down with only his head showing. In the photo above I have circled him. He has rudimentary horns, unlike the youngster at upper left.
This second photo, above, is what the area looks like with a lens that mimics the field-of-view of human eyes (that is, a 40mm lens) versus the 280mm telephoto setup used for photo #1. Believe it or not, three of the sheep (within the circle) are visible to the naked eye because of their white butts. Admittedly, I have 20-10 corrected eyesight but most people with normal vision ought to be able to do as well.
For those out looking for sheep on your own I think the most helpful advice I can offer is to look for the white butts of the sheep. I just use my eyesight as I always forget to take binoculars with which to glass the slopes.