Broadside
Hold on the back line of the near front leg, a third of the way up the body. An ibex's chest is deep and the heart sits just above the elbow. The billy's winter coat and beard hide the leg line, so glass for the elbow before you settle the reticle.
Quartering and other angles
Shooting steeply downhill, hold higher on the near side so the bullet exits low through the far lungs. Uphill does the opposite. Quartering away, aim for the far front leg.
Do not
Do not shoot an ibex above a drop you cannot reach, and do not guess range across a valley. Mountain range is almost always further than it looks.
Where they live and the typical miss
Alpine ibex live in the Alps and Spanish ibex in the Spanish sierras; other ibex species are found across Central Asia. The typical miss is high, caused by misjudged range and steep angles.
Wind in the mountains
Thermals rise in the morning and fall in the evening. Plan the stalk so the rising or falling air carries your scent away from the ibex, and allow for crosswinds on long shots.