Lone deer are one thing...be very aware of adults with fawns.

My dog was once attacked by a huge deer that had just given birth. I stood between my dog and the deer (before I knew why the deer was chasing my dog) and the deer came after me. Luckily, I was right in front of our deck, so I bounded up it and got inside. The deer then turned and left and I noticed blood on it's rear.

It was not 2 minutes later when we saw it through the trees nuzzling a tiny baby, barely standing and wet!

In that same neighborhood (where deer out numbered people about 10 to 1) I had other deer showing agression when their offspring were close. So I'd say deer have three thoughts "Is this good to eat" "Makin' babies" and "protect the young".