what happens when a leader retired?

So my lead wolf is like almost 7 years old, and shes probably gunna pass or ill retire her very quickly, but can someone tell me exactly what happens when ur lead passes away? i looked around but i cant rlly find anything!
any help pls?

Your lead passes at 8 years old, and you immediately have to choose a new lead from the wolves in your pack - it can be an adult, adolescent or pup (in which case the wolf will be aged up to 1 year). 

When you change leads you’ll loose all scouting progress on the explore map, although you’ll stay at the home biome you’re currently in.