— Geirshnae can spawn anywhere in the southeast valley of Cliffs of Moher. That's a pretty big area. (See map below.)

— After he spawns he's restricted to a small roam area. (For an explanation of roam areas and spawn areas, click here.)

— He spawns shortly after dawn and despawns (disappears) at dusk.

— He doesn't spawn every day. It's not unusual for ten day-night cycles to pass before he spawns.

— You don't have to kill anything to make him spawn.

Putting these facts together, here's an easy way to catch him. Park a toon in his valley. At about 9 am game time, run through the valley to see if he popped. You'll need to make a few passes to see the whole area. If he's not there, park the toon and come back in about 45 minutes when it's 9 am game time again. Repeat until you see him. It's not unusual to do this ten times or more before he appears — but that takes only 30 real minutes in total so it's not a problem.

Geirshnae was one of the original trophies added to the game in 2003.