SOME SUGGESTIONS FOE BIED STUDY. 121 



CUCKOO (S.V.). A bird about 14 inches long, of slender 

 and shapely build, bluish grey above, front and sides of the 

 neck lighter, under parts of the body bluish-white with 

 narrow transverse bars of brown. Quills brownish, inner 

 webs barred with white, tail feathers dark grey spotted 

 along the shafts and on the inner web, white at tip. The 

 bill is slender, with a slight downward curve. This bird 

 arrives in this country in the end of April and leaves in 

 July or August. Its cry, "coo-coo," is well known, as is 

 also its habit of depositing its egg in the nest of another 

 bird. 



Some notes with regard to its egg-laying habits may here 

 be given. Its egg is small in proportion, being scarcely an 

 inch in length. It is greyish white, reddish white, or very 

 pale light green with greyish brown ; sometimes it is plain 

 blue without speckling. It is in fact somewhat variable 

 as regards colour. The egg is laid on the ground and 

 carried in the bill to the nest of some other bird. This 

 nest is frequently that of the Meadow Pipit, Hedge 

 Sparrow, or Bullfinch, but a great many different birds are 

 victimised.* 



In the Fenton Collection of Eggs at Aberdeen Univer- 

 sity 101 different clutches occur in which a Cuckoo's egg 

 has been found, and in these 57 different kinds of birds 

 are represented. These include Song Thrush, Blackbird, 

 Eedbreast, Garden Warbler, Swallow, Skylark, Goldfinch, 

 Wren, Hedge Sparrow, Meadow Pipit, Bullfinch, etc. An 

 analysis of this collection shows : 



(1) The Cuckoo's egg has considerable range of colour 

 variation, i.e. in a series. There is also what may be 

 termed discontinuous variation, e.g. the plain blue egg. 

 While this is so, there is some evidence to show that the 

 eggs of individual cuckoos probably do not greatly vary. 



* In certain localities the Cuckoo shows a preference for certain 

 birds' nests, probably because these are numerous and readily found. 

 Mr. Fen ton informs me that "in Pomerania the common wren is 

 the usual victim ; at Evesham, in Worcester, the reed warbler ; at 

 Clitheroe, the yellow wagtail ; and in the western islands of Scot- 

 land, the twite." 



