Dumdum: The fields adjacent to my home have BOTH Whitetailed Deer and Mule deer in them - many more Mule Deer than Whitetails.
95% of the time they stay separated by hundreds of yards - the other 5% of the time they do intermingle!
The exception to this is when Whitetailed Does are harvested and their orphaned fawns will STAY with the Mule Deer groups - I don't know why.
I have pictures of my front lawn with both Mule Deer and Whitetailed Does feeding within feet of each other - I have 11 Mule Deer Does in my front yard right now but NO Whitetails in sight.
Myself and one of my Hunting partners harvested a nifty hybrid (Whitetail/Mule Deer mix) along the Greybull River near Meeteetse, Wyoming - the taxidermist in Cody, Wyoming eagerly sought the cape of our Hybrid Deer for his use and paid us appropriately!
I will say this one of the "Mule Deer" Does that frequents my lawns has VERY small Whitetail like ears - I will pay attention to her tail next time she comes by.
Love watching them all.
Hold into the wind
VarmintGuy