@mo There's quite an abondance of food there for hungry wood mice; plenty of crowberries up in the screes (dark green on the photo), plus an orgy of all the grain from the Leymus arenarius pictured in the foreground.

https://en.wikipedia.org/wiki/Leymus_arenarius

@mo Think it must have been one of the first nights with serious frost, most of those mice must have been youngsters who hadn't figured out that it was already time to prepare the winter dugouts.

@mo OK, another anecdote for this place:

Sometime last century [sic] I put up camp with one of my groups under the slopes to the right of the mountain. It was a calm, cool and starry autumn night in late September, perfect to chill out after a 3 day hike from Snæfell to Lónsöræfi.

Just after midnight the calm was broken by some terrible cries from some of the tents; tens of thousands of wood mice swarmed around, and quite a few managed to squeeze through the zippers of the tents.