In continuously grazed pastures used only in the summer time, cattle may graze everything else and leave the fescue in the spring. The clumps get bigger over the summer as the other forage gets grazed harder and harder. It is very common to see fields with clumps of tall fescue and very short grazed bluegrass-white clover between the clumps.
On the winter kill issue, the more southern types of fescue might winter kill in MN, but a lot of the improved varieties persist well up into Canada. We see double digit (F) lows here every winter and frequently without snow cover and I've not seen any tall fescue winter kill in ID.
JR