Grey Phalarope: Feeding association with Coot?

The Grey Phalarope (Phalaropus fulicarius) breeds in the high Arctic, usually in remote areas such as northern Siberia, Alaska/Canada, Greenland and Svalbard - in fact, Iceland is its most southerly breeding location. It winters at sea around cold current upwellings where food is abundant, mainly off the west coasts of South Africa and South America. As it also migrates across the sea, it is rarely seen on passage, although a few appear on the mainland (generally coastal locations) especially if blown by strong winds. 

Grey Phalarope © Dean Eades

With breeding in such inaccessible locations, and both wintering and migration taking place out at sea, it's not often that the opportunity arises to see one in southern England. Most British records are from Scotland, though I had seen two before at Strumble Head, Pembrokeshire, Wales - one of the most regular areas for sightings. So, it was a pleasant surprise to see one at Fishtail Lagoon in the Keyhaven & Pennington Marshes, Hampshire while out for a group walk on 7th November 2010. British sightings like this are in winter plumage (as above) and the bird, although a wader, looks superficially like a tiny gull - the individual at Fishtail Lagoon did however have a faint blush on the throat, an indication that it was a 1st-winter bird.

Grey phalarope show interesting feeding behaviour, spinning, often in tight circles, to stir up the invertebrate food that they take from the surface. Studies (e.g. Hohn 1971) have shown a tendency to spin clockwise, especially if there are many in the same feeding area, although individuals may spin both ways.

To add to the interst, this individual was seen apparently feeding in association with Coot (Fulica atra), closely following one actively foraging bird and feeding from the surface around it, presumably taking food particles stirred up by its diving. Having since looked for sightings of this individual (which I now know had been present for a week or two), this behaviour had been noted at least once previously. I am however unaware whether this feeding association is typical behaviour for the species - certainly the similarity in scientific names between Grey Phalarope and Coot is simply due to the coot-like structure of the phalarope's feet. So, although it is likely that observations are limited by the remore areas this species frequents, I would be interested to hear if anyone knows more about this type of feeding association.

Reference

Hohn, E.O. (1971). Observations on the breeding behaviour of grey and red-necked phalaropes. Ibis 113(3): 335-348.