Here's the deal---sex hormones can be conditioned by the amount of "photoperiod". For seasonal breeders (and each species is different), the relationship of certain hormones to one another will determine when females come into estrus.

Bucks are conditioned similarly, but produce androgens, primarily testosterone and related by-products. With decreasing photoperiod, the amounts of testosterone rise in bucks and estrogen concentrations rise in does.

But here lies the controversy/mystery...photoperiod is simply the amount of "light" in a 24 hour period. The moon does cast appreciable light---go out tonight and tell me, if the skies are clear, that there is not an appreciable amount of light outside. This was the initial observation that led to many of the moon phase theories. And one of the current theories resides with the full moon acting as a trigger for the final shift between prolactin/dopamine/estrodiol hormones for the onset of estrus.

The decrease in light heightens the animals sensitivities, then the intensity of the full moon around Nov. 01 (in the Northern states) triggers a surge of estrogen which shifts the hormonal relationship, resulting in what we hunters call the "rut".

And to my knowledge, there are various scientific studies that indicate the moon theory is bogus. However, for every one that disproves the moon, there are 2 that counter with favorable evidence.

But the real answer to your question is simply...when the does are ready to breed.

Bucks are ready as soon as you see the first scrape or the first rubs on aromatic trees. Many older bucks will use one primary scrape, then incorporate scrape "posts" on aromatic tree species such as cedar or hemlock. Find these and you not only have a rubline, but also a scrape line---this is a big indication that the rut is close, you're probably hunting a mature buck and "HUNT HERE" is a given.

There is also a less known fact about mammals and reproductive function, which is based on high protein diet. Women with a high protein diet will experience menarche much sooner than those on poor diets, and seasonal breeding mammals (such as sheep) will begin ovulating (estrus) much earlier in the season than those on poorer diets.

So in essence maybe the rut really coincides with what the animal eats year round, how early the oaks drop their acorns and when the farmers cut their cornfield.

For now though, I'll personally just stick to what I see in the woods, because that's really the only true and tried answer you can rely upon. The rut will move from year to year, and if you're off by a week that could mean the difference between seeing a yearling 4-pt and a 4.5 year-old 10 pt.

S&R