Strange Bed Fellows

The family on this drain has grown. It once belonged to a single bird.
As we see here there is now a family of 3 living together in peace. I did spot another turtle come up and have a chat with the turtle here but after a brief exchange of head nods the swimming turtle swam away and descended back under water.

I was briefed by another walker, that a family of 5 turtles float around in the water. It would seem the family here would allow one more turtle on board, but maybe they have rules.

No visiters!
The one bird is perched on top a stick.
Is it to fight off others, or for their pet turtle to climb up on?