Here's Steve Bartylla's theory he posted on Facebook a week or so ago.
"So, yesterday, we shared a photo sequence of a buck glued to a doe's tail, on Sunday, moments before my close, young friend, Parker, shot him. I mentioned I get into that more today.
What I'm about to cover does NOT apply to the north/areas still receiving nasty winters. We're specifically talking the mid states of IA, IL, IN, OH belt.
Way more than we tend to realize, overall weather conditions have historically been Mother Nature's great standardization tool, in the Midwest and points N. Yes, it's the amount of light in a 24 hour period that dictates a glut of things, such as when bucks shed velvet and most certainly when the does enter estrus, once they reach 1.5 years of age and older (as doe fawns, entering estrus that first fall is based on reaching physical and physiological thresholds that first fall/winter).
Here's the catch, though. The exact amount of daylight that triggers these acts are based on when the deer are born. So, if the birthing doe fawns early her doe fawns will enter estrus early. If the birthing doe fawns late her doe fawns will enter estrus late.
25+ years ago, in the Midwest and points N, our winter weather patterns were COMPARATIVELY way more consistent. Sure, some years had more snow than others and some winters tended to colder, but you could pretty consistently count on it starting to get cold by the end of Oct and warming in about the same window each spring.
With that weather structure in place, most fawns born early died before summer and those born late had the high tendency of dying over winter, keeping the breeding window pretty tight.
Today, In the MOs, IAs, ILs, INs & OHs of the world, our "winters" are as consistent as a pair of dice trying to roll the same two numbers each time. Sometimes it will happen, but it's mostly all over the place. In turn, the breeding has went from mostly (no where near all, but closer to 100 than 50%) occurring in less than a month to now stretching to 3 or more months.
All of that for the point. What I've noticed this time of year is an emerging trend for the mature bucks to start actively breeding in Oct and running into Jan. Yes, Nov is still hotter in the % of estrus does than Oct, Dec or Jan, but the level of breeding in those outside months keeps just going up, as evident by more and more spotted fawns deeper and deeper into each season.
In my experience in those Midwestern states, Nov is still relatively normal, though not as intense as it used to be. That said, the mature bucks aren't settling into the bedding, feeding and tending the sporadic doe fawn entering estrus late patterns one see's in the north, this time of year.
Instead, I've noticed the theme in more recent years of bucks going into a hybrid of tending scrape lines, again, as if it was Oct, while still somewhat keying on food as is normal in late season, and cruising way more than they historically had in Dec & Jan.
They're comboing the pre rut, rutting and post rut behaviors. They're doing some scrape line tending and cruising, but not as much as earlier. They're still hitting food like late seasons of years gone by, but nowhere near as focused on just the food and still checking most does, almost as if it was Nov.
In my experience, specifically in the lower belt of Midwestern states, the mature buck behaviors are literally changing the more our weather "patterns" go nuts. Some of my very best stands in Dec are now actually covering scraping activities, these days, as if it was still Oct.
No real suggestion in this one, other than truly observing what the mature bucks in your area are actually doing, instead of what they used to when we had way more consistency in our weather "patterns."
Then, merely cater your tactics to the reality you see, not based on what we're told they're doing, as what we've been told in these regards is getting less and less accurate, in my experience, in the states below MN, WI, MI and such (though the S ends of even those states are stretching too, just not as much).
As always, take anything of value and merely pitch the rest. Also, keep in mind that those hunting C MN and points north are not seeing the same results as those in southern Iowa, as it applies to the rut cycle. Central MN still has a way more consistent winter, forcing the rut cycle to stay tighter".
