464 SANDPIPERS AND RELATED SPECIES 



flight. Before one has had time to realise that it has taken place, 

 most of the various species have sorted themselves into groups. The 

 dunlin, in a compact mass, probably wheel out to sea at first, gradually 

 circling back to a more distant part of the ooze, to alight and continue 

 feeding as before. But in the interval of flight one has had time to 

 wonder at the marvellous orderliness of the evolutions they perform. 

 The movements of the birds are so well timed that, however suddenly 

 the direction of flight may be changed, there is always the most perfect 

 harmony of movement. As the birds, simultaneously turning, present 

 first their upper, then their under surfaces to view, the flock appears 

 at one moment as a dark mass, and the next silvery light against the 

 clouds or sea. It is not that this habit of orderly flight distinguishes 

 the dunlin from all other Waders, but either it is more perfectly 

 developed in this species, or the greater size of the flocks makes it 

 appear to be so. To see it to perfection one must visit one of the 

 more extensive, richer feeding-grounds, preferably near the mouth of 

 a large tidal river. I have often seen them in the Wash, where 

 numerous vast sand- and mud-banks, left bare by the ebb, form feeding- 

 grounds for countless thousands of dunlin and other Waders. They 

 continue feeding until the flow of the tide lifts them off' their feet, and 

 then, as the birds from the various banks gather together and wend 

 their way to regular resting-places, there may be witnessed the truly 

 wonderful sight of enormous flocks consisting of thousands of birds. 

 This is always most impressive towards the close of a winter's after- 

 noon. As the massed ranks sweep by one catches for a brief spell the 

 musical swishing of innumerable wings above the murmuring of the 

 tide as it creeps gently over the shallows. For an equally brief spell 

 the rapid regular wing-beats of the birds are to be distinguished. But 

 as they pass in the gradually lessening light, so perfectly regulated are 

 their movements that individuals and individual action are lost to 

 sight, and there remains only the impression of an undulating living 

 cloud, guided in its progress by a single impulse. Rhythmically it rises 

 and falls, at one moment spread out like a long low distant headland, 



