332 THE A'ESTS AND EGGS OF BRITISH BIRDS. 



almost invariably made in the water, cither floating and 

 moored to the reeds, or built up from the bottom of the 

 pool in the same shelter, the matter bein;^ purely a 

 question of the depth of water. It is a huge heap or 

 raft of dead aquatic muddy vegetation of all kinds, with 

 a shallow depression at the top more neatly hnishcd, in 

 which the eggs are laid. Several mock nests are gener- 

 ally to be found in its immediate neighbourhood, made 

 whilst incubation is in progress, and most probably 

 destined for the use of the young as resting-places. The 

 bird sits lightly, covering its eggs (but not so effectually 

 as the preceding species) with pieces of wet v/ecd, and 

 slipping off them into the water the moment it is 

 alarmed. This Grebe, even though gregarious, resents 

 intrusion, and will attack and drive off any other Grebes 

 that may trespass on its own particular retreat. 



Range of egg colouration and measurement: 

 The eggs of the Great Crested Grebe are from three to 

 five in number, very rarely six, and most generally three. 

 They are white when newly laid, more or less chalky in 

 appearance, elliptical, and pointed at each end. When 

 held up to the light the interior of the shell is deiic ite 

 green. Contact with the wet nest and the feet and 

 plumage of the bird soon robs them of their purity, sg 

 that specimens without ochre-tinted stains are somewhat 

 difficult to get. Average measurement, 2*2 inches in 

 length, by v^ inch in breadth. Incubation, performed by 

 both sexes, may be about a month, but nothing definite 

 appears to have been decided. 



Diagnostic characters : The eggs of the Great 

 Crested Grebe may be distinguished from those of any 

 other species breeding in our area by their size, colour, 

 and elliptical shape, usually as much pointed at one end 

 as the other, or nearly so. 



