They shall not pass

The two swans who caused so much trouble for the young couple with their two cygnets were at it again today. However they picked on the wrong family this time by flying up to the sluice end where the swan parents with the five cygnets live. Those cygnets have been trained well. As soon as they saw the intruders the cygnets sounded the alarm and three of them positioned themselves, wings fluffed up, to form a barrier. That allowed parents time to come over and show the offenders the way home. Their flattened backs say it all. 
Extra is dad showing who's boss.