I want to know the answer to the following question:
It appears that otters may be returning to the city of London after how long an absence?
All the background I'm provided with is that "Ten of England's eighteen species of bats have been recorded in Epping Forest: soprano, nathusius and common pipistrelles, noctule, serotine, barbastelle, daubenton's, brown Long-eared, natterer's and leisler's.". Is that enough to answer the question?