Rookiedog is 4 and generally pretty well behaved albeit with a propensity to chase squirrels.
Recently he has started barking when he sees random males - generally ones on their own and without a dog. He's the least aggressive dog ever, but it still must be scary for those on the receiving end. I don't want to have to put him on a lead for all of his walks as we live in a rural area so we rarely bump into people, but I cannot have him doing this to other people.
Any thoughts on why he is doing it and how we can stop him ?