Mobben

= to bully.

I thought this swan was swimming along just to get from A to B, but no, out of (my) sight were two other swans, minding their own business.  This swan is clearly the bully boy of the river and scared the other two off up stream.

I thought bullying was a childish trait that we leave behind on the playground, clearly it's an animal instinct that some people never grow out of.