When do bucks start moving?

[profj]

While on a fruitless search for high altitude elk in muzz season, I saw a metric shit ton of nice muleys (at around 11-12k altitude above treeline). Checking the points situation, I might be able to score a first rifle season tag (in CO), that's usually the second week in October. So, I'm wondering when the bucks start moving down, and what affects that, like eg. big snow early in the year?

 

[Matt5266]

Two major factors that I've noticed over the years with deer. Snow and pressure. 2 biggest factors in them moving.

 

[Greenbelt]

In my neck of the woods it seems to be the snow and real bad weather that starts the move.