In my experience, the mule deer are at the upper elevations,
the black tailed deer at the lower.
The mule deer in the
Tahoe area have taken a big hit from habitat loss and fragmentation. Where I used to be able to count 70 deer along
highway 89 driving at night, (20 years ago), now you will
be lucky to see one.
The town of Truckee is 100 square miles alone. Second largest city by area in CA after LA. (The dog catcher
has a big job).
Reno's new Del Web development of 10's of thousands of homes is right on top of the mule deer's winter grounds too.
Mule deer don't do well with human pressures.