328 THE NESTS AND EGGS OF BRITISH BIRDS. 



fragments, lined with grass. Instances, however, are on 

 record where the eggs have been found on the bare 

 earth. One would think that this Diver must occasion- 

 ally remove its eggs in the event of a sudden rise of 

 the water, so closely are some of the nests made to the 

 margin of the pool. The bird is not a close sitter, 

 slipping quietly off the moment she is alarmed, and 

 taking refuge in the water, where she is soon joined by 

 her ever-watchful mate. Sometimes the birds will fly 

 round and scan the scene from the air. 



Range of egg colouration and measurement: 

 The eggs of the Black-throated Diver are two in number, 

 narrow and elongated in shape. They vary from olive- 

 brown to rufous or buffish-brown in ground colour, 

 sparingly spotted and speckled with blackish-brown, 

 and with a few obscure underlying markings of paler 

 brown. The spots range from the size of a pea down- 

 Avards, and are distributed here and there over the 

 surface, and are generally more numerous towards the 

 larger end of the egg. Average measurement, 3-2 inches 

 in length, by 2*0 inches in breadth. Incubation, per- 

 formed chiefly if not entirely by the female, is said to 

 last a month. 



Diagnostic characters : The eggs of this Diver 

 are best distinguished by their larger size and less 

 profuse spotting, but inasmuch as they overlap (rarely) 

 in measurement with those of the preceding species, 

 careful identification is imperative for perfect accuracy. 



