What's at the end of the Rainbow?

Driving along the Ancient Highway a sudden heavy shower produced a fantastic Rainbow.  I really needed to have had a 20mm lens with me to take in the whole panorama, but here are the two ends of the rainbow.

If you've ever wondered if there's a pot of gold at the end of the Rainbow, or if not5 what is there I will  tell you what I found today. The left hand end came to ground somewhere near to the Restharrow Hide, so that one was possible to research.

The right hand end was dropping into the sea, beyond the seawall, and lacking a wetsuit I decided to leave that end a fishy mystery.

I already knew that the field next to the Restharrow Scrape had a small flock of white-fronted Geese grazing early in the morning, so I was on my way to see id they were still there.

By the time I arrived the Rainbow had departed by the geese were still there, but very distant. Fortunately the light was by now very good and the views through a telescope weren't too bad. There were around 18 birds, but there was no way of getting closer and therefore the photos remain a record of distant dots.

 There were a lot of Teal on the scrape, where the water level was as high as I've seen it. But it was a group of Gadwall and Tufted Ducks that caught my eye.

 There were four Tufted Ducks, a pair and two females together. They were very active and diving frequently.

 There were around eight Gadwall with them, and they stuck pretty close by the Tufted Ducks each time that they dived.

I've often seen Gadwall behaving this way, normally with Coot. They wait around for the diving bird to surface and bring up pieces of food that they can snaffle. I suppose that this is a form of kleptoparasitism, although it is a passive type, unlike Skuas harrying Terns.