The heft: territory memorized by flocks
Herdwick ewes on unfenced common fell stay on their own patch of hillside, their heft or heaf, because each ewe learned its boundaries from its mother as a lamb. That knowledge lives only in the flock and passes down the generations. If a hefted flock is wiped out, as happened when the 2001 foot-and-mouth epidemic brought mass culls across Cumbria, new sheep cannot simply be bought in to replace it. The land has to be painstakingly re-taught.
