Driving From Behind

I was on the towpath, crossing the new bridge across Seneca Creek, when I saw this sight on the Potomac river yesterday. The parent duck (from its haircut I think it is a female Common Merganser), which had been leading its little ones towards the middle section of the river, changed direction and headed back towards a section of the Maryland shore that was hidden from my sight. I suspect that the duck had just noticed me on the bridge, sensed danger, and was looking for protection for its brood.

I can understand that the parent duck likes to keep all its ducklings in its sight in front of it when they are headed out somewhere as a group, but I do not understand how it manages to direct the direction of their swimming from behind, and keep them in a straight line when doing this. What kind of natural intelligence is in play at this point? Notice that this is happening in spite of the distance between the parent and the little ones in this case. There could be some audio communications going on, I suppose.

The thought also occurs to me that this is a very dangerous situation for the brood to find itself in. There is no way to escape other than by diving underwater if there were an attack by a predator bird. There must have been a good reason why the parent duck had set out on this hazardous journey across the river.

There are always a lot of interesting things going on in nature.