The paper is suggesting that sheep in herds tend to follow each other, and in that sense end up with "leaders" - that is, a single or relatively few animals tha

The paper is suggesting that sheep in herds tend to follow each other, and in that sense end up with "leaders" - that is, a single or relatively few animals that are able to direct the herd as it moves for a short while. Reminds me of watching boids Makes sense. Honestly we do this too - when travelling in large crowds certain people take on the role of leader (one person parting crowds who is large or particularly determined to get to their friend or just happened to be first, and chains of others follow them because it's the right general direction as well and is easier than pushing through oncoming traffic)