One common theory suggests that moon phase can influence timing of the rut, and therefore peak activity periods. We know the onset of breeding season is influenced primarily by photoperiodism - changes in the amount of sunlight as the days grow shorter. This causes physiological processes in deer that trigger their reproductive system. Light is light, right? So one could easily conclude that changes in the amount of moonlight might also have an effect. And because the full moon does not occur at the same time annually, peak breeding dates would change from year to year, possibly by as much as a couple weeks. It sounds good in theory, but to date there is no peer-reviewed empirical evidence to support it. For any given location, peek breeding dates occurred at the same time every year, regardless of changes in moon phase timing.