Humans using Tracking skill at night-difficulty?

[thom]

So my players repulsed a night-time assault by an orc band; and (for next session) they want to pursue the fleeing, Reeling (condition) survivors & finish them off. They have Continual Light (daylight) stones, the terrain is rolling hills, and the orcs (obviously) weren't concerned with hiding their tracks while they fled. I'm trying to figure how hard it'd be for humans to track at night. Thoughts?

thom