Sorry for the delayed reply NitroX!
Unfortunately, I wasn't able to accompany my dad. A week of hunting (and passing on smaller males) led to a huge animal presenting itself at 550m which was too far away.
Fortunately, he is going back to give it another bash before the season ends. He e-mailed me today (Sunday) and will be hunting on tuesday if the snows are not too hard. Apparently the ibex have decended the slopes considerably since November.

Fingers crossed!