I've lived in MT my whole life, hunted for 23 yrs. Here is what I have observed concerning mule deer.
1. Increases in elk number = decreases in mule deer numbers. I've witnessed this across several mountain ranges. There are 2 main reasons for this. First, as forests mature and primary successionary plants are replaced by grass and trees, habitat is more conducive to elk than mule deer. Secondly, elk are much more competitive than mule deer and can displace them on the landscape.
2. Whitetail deer competition with mule deer. This was very evident in NE MT this year. Some areas experienced massive die offs of whitetail due to EHD. Creek bottom habitats normally 100% whitetails were almost 100% mule deer. This suggests that mule deer are displaced from thos habitats by whitetail deer, not by habitat needs.
3. Hunting pressure is not static and "flows" around the state. Currently, certain areas of Eastern MT are absolutely inundated with NR and R hunters alike.
4. Age class is very difficult to observe and quantify without mandatory reporting and a concerted effort to age mule deer. Do I think age class is decreasing....I dont know, we kill some OLD bucks regularly. Do I think most people are shooting young bucks....absolutely. I tend to think that there is more mature animals on the landscape than we realize.
5. Decreasing doe numbers probably equals bigger bucks, for 2 reasons. First, decreasing the number of animals on the landscape means more nutrition per animal. Second, if individual does are healthier they produce healthier fawns. These healthier fawns, if male, produce larger antlers over their life time. I have seen this with certain age class of bucks over time in MT and it has been demonstrated in resesrch in WY.
6. MT changes doe tag allocations to align with population trends they are seeing. R 7 generally has 10-11k mule deer doe tags. This year was less than half of that due to a 30-40% drop in population due to acute, extreme drought.
7. I think the long term future of mule deer in the entire West is bleak. I base this mainly on habitat. In mountainous areas mule deer are losing critical winter habitat to development at a staggering pace. In the plains and SW increased drought length and intensity are limiting habitat and numbers.
8. I think people want the solutions to be as easy as "stop hunting them during whatever period". Its not. The West is full of different strategies for hunting mule deer. With a few exceptions, mule deer populations are decreasing across all areas. This alone is evidence that season structure isnt the "golden ticket" we all think or want it to be.