[diggan]

This sort of "herding behavior" isn't just noticeable when you go out to swim, but any time 1+ people are apart from each other. You can spot these dogs extremely easily when you have a bunch of young children playing together, and you can see the family dog paying attention and as soon as one strays away from the group, the dog will start engaging and carefully nudge the stray kid back to the group.

There is no inherent danger in those situations, yet the dogs prefer if everyone was together in a group. If that's not "herding", I might just not understand what herding really is.

[krisoft]

What do you describe sounds like herding behaviour, yes. When I say it is not a good description for "this" I mean the behavioural difference between Arthur and Lenny. Maybe you read it as if I don't believe in herding in general? That would be indeed silly on my part.