best time of year for wildlife photography Colorado

I posted this in general discussion and was advised it might be good to post here as well.

Anybody care to offer opinions on this?  Planning a visit 2017 for 10-15 days.  Hard to get reliable info from Internet searches so figure here's where the experts will be.  Summer I fear will be too crowded with wall to wall traffic.  Winter, not interested due to so many areas closed or limited access.  I think I've gathered Autumn is probably primo but then Spring seems pretty doggone good too and I'd rather go sooner than later.  I've never been to the state so I am totally clueless.

Any advise or opinions will be much appreciated.

Thanks,
 

What type of wildlife are you wanting to photograph?  Mammals or birds and what species.  Each have their prime times to see and photograph.
 

Bull elk in velvet in August will be found in the open more than after they rub.  Late September in the rut when they bugle is a great time.  I do not know if RMNP has changed some access issues, but it has offered good opps during the rut based on images I have seen.  Maybe Mt Evans after they open the road to see mountain goats before they shed and become raggy, or right before Labor Day when the road may close at the top.  Pica and marmots would be a good on a mid to late July wildflower trip in the mountains basins.

Remember Spring comes late in the mountains.  At higher elevations it starts mid-May at the earliest.