More bird oddities

I was looking at that amazing picture of the rook and it reminded me of a strange Sand Martin I saw the other day in Llanfair Clydogau. To start with it was acting a little strangely i thought since there were no others of its kind nearby and instead it was circling a bungalow along with 4 House Martins which were clearly nesting there. What caught my eye however was the fact that it had a large white object dangling behind it, giving it the appearance of long tail streamers. The object was about twice the size of the Martin and could have been wool/paper/plastic/feather perhaps. I couldn't tell how it was attached but it seemed not to be hindering the bird to a great extent.