Well, if I remember correctly, Orcs arn't exactly subtle creatures, we could go to the camps, and as the are high up, survey the surrounding countryside for signs or orc destruction? Large amounts of felled trees (if there are any, which I doubt) or amounts of slaughtered animals and stuff like that
Well with no ranger I have to default back to other ways of ensuring you find them from here.
If there were obvious signs of destruction you would have found them a while ago- the disappearing livestock was the best clue there, but it seems they were hiding the slaughtered animals.
(Because Orcs are actually just a tad more wily than you might think. More so than Dunlendings).