We're in the top of the Snoqualmie valley and we get valleyset a bit less than an hour before true sunset. The girls usually stop ranging so much around the start of valleyset, getting closer to the coop in their foraging, until they put themselves away. If they aren't out, they'll usually start bickering over roosting perches just about the time I notice it's getting dimmer. They're pretty consistent about responding to solar cues, even given the relatively large variance in day length this far north (yes, the Canadians here can mock me, but compared to California it's a lot).