SOME SUGGESTIONS FOR BIRD STUDY. 93 



(c) In many cases the colour renders the eggs difficult 

 to observe. To appreciate this fact one must view the eggs 

 in the nest in their natural surroundings. Objects such 

 as bright blue eggs which look conspicuous in the hand 

 may be readily overlooked in the confused light and shade 

 of a thick hedge. Further, there are some clear cases in 

 which the eggs closely resemble their immediate surround- 

 ings. Examples are those of the terns, which resemble 

 the pebbles of the beach amongst which, they are laid, or 

 the plovers whose olive-green eggs speckled with brown 

 are like the ground on which they lie. Both these birds 

 nest in exposed places. 



(d) We also notice in many groups of birds a kind of 

 " family resemblance " in the colour of the egg. Take, for 

 example, the crow family E-aven, Carrion Crow, Hooded 

 Crow, Rook, Jackdaw. The eggs of these birds laid side 

 by side are seen to be but variants of a greenish tint with 

 light brownish speckling or blotching. 



The members of the G-ull family have eggs of different 

 shades of olive green with brownish black blotching. The 

 hawks exhibit a brick-red pigment in varying quantities 

 upon a light- coloured egg. 



The various species of Tits have white eggs with reddish 

 spots. And other cases might be quoted, e.g. breeds of 

 domestic fowl. Investigation has suggested that the 

 colouring matter is derived from the blood, and is of the 

 nature of a waste product. If this is so, the family 

 resemblance which is recognisable in many cases is not 

 difficult to understand. The colour of the egg in such a 

 case may be regarded as a matter of family constitution. 

 But perhaps with our pupils it is best to be content simply 

 with a clear recognition of the facts. 



(e) Note lastly that in some cases there is very great 

 individual variation in the matter of colouring, e.g. Guil- 

 lemot. (Incidentally note the marked constancy of shape 

 of this bird's egg.) 



Before passing from this subject, the appearance of a 

 few of the commonest eggs of birds should be noted. 



