Humans don't flock, of course. They march or gather or group. And "drafting," as mentioned in yesterday's post, only occurs at relatively high speeds. Thus, the guys playing the flutes are only able to get by with less effort than those in front of them because they were smart enough to pick little instruments. Notice the white leg guards on the drummers, by the way. I wonder how long that piece of equipment has been part of the uniform?
I should mention that this is the changing of the guard at Buckingham Palace in London. Tourists flock there on a regular basis to witness the spectacle. Did I say "flock?" I meant "gather."