Spent an afternoon in very cool blustery weather at Castle Howard Lake. I have never seen so many Hirundines(swallows and martins). I estimate 2000 darkening the skies and feeding literally from the surface of the lake, flying into wind and dipping their heads to touch the surface of the water to take hatching insects. The spectacle was quite remarkable, but alarming at the same time, for many birds seemed to be really struggling. To the the north of the lake swallows were exhausted, resting on caravan rooves and even on molehills. The swifts were flying exceptionally low taking insects inches above the water and at times missing me by a few millimetres. In all, and it was impossible to count them accurately, I would make a wild guess at 1000 swallows, 500 sand martins, 500 house martins and at least 500 swifts.