The only difference that I have noticed in the years I've hunted elk, are that they aren't in the clearings for very long after first light. Becuase they've had some "light" all night to feed,I think they spend less time mingling in parks and clearings in the mornings. When there's not a full moon, you may have til 10am in an unpressured area, I've noticed that once first light comes (during full moon), you'd better be close already or be able to get to em in less than an hour.