118 ESSAYS OF A BIOLOGIST 



like the colonial Herons and Egrets, it makes every 

 effort to conceal its nest, this cannot take place at 

 its most natural moment, that of nest-relief, but must 

 be made to happen out on the open water where there 

 are no secrets to betray. If the sitting bird wishes to 

 leave the nest, and the other does not return, it flies 

 off, after covering the eggs with weed, in search of its 

 mate; it is common in the breeding season to see a 

 Grebe in the ''search-attitude,'' with neck stretched 

 up and slightly forward and ear-tufts erected, emit- 

 ting a special and far-carrying call. When this call 

 is recognized and answered, the two birds do nothing 

 so simple as to fly or swim to each other, but a special 

 and obviously exciting ceremony is gone through. 

 The bird that has been searched for and found puts 

 itself into a very beautiful attitude, with wings half- 

 spread and set at right angles to the body, ruff erected 

 circularly, and head drawn back upon the shoulders, 

 so that nothing is visible but the brilliant rosette of 

 the spread ruff in the centre of the screen of wings, 

 each wing showing a broad bar of brilliant white on 

 its dusk-grey surface. In this position it swings rest- 

 lessly back and forth in small arcs, facing towards its 

 mate. The discoverer meanwhile has dived; but, 

 swimming immediately below the surface of the wa- 

 ter, its progress can be traced by the arrowy ripple it 

 raises. Now and again it lifts its head and neck 

 above the water, periscope-wise, to assure itself of its 

 direction, and resumes its subaqueous course. Nor 

 does it rise just in front of the other bird; but swims 



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