292 Habits of the Cuckoo. 



differently conditioned eggs, were hatched at the same time. 

 In this statement we learn, too, that the interchanged eggs 

 were identical in kind, and that this kind was that proper to 

 the species of bird to which they were introduced : the eggs 

 differed only in their condition. Montagu has remarked, in 

 continuation, that " Birds will sometimes discriminate the 

 egg of another species, and will turn it out." It is clear that 

 all those pairs of birds which have been known to have 

 hatched the cuckoo's egg have either not discriminated it, or 

 have not turned it out. The egg of the cuckoo is, too, more 

 or less dissimilar to that of the eggs among which it is intro- 

 duced. A comparison of its weight and size with those of the 

 eggs of certain other birds is already quoted above. Montagu 

 has stated that the egg of the pied wagtail " exactly resembles 

 that of the cuckoo." (Rennie's Mont. Orn. Diet., p. 378.) 

 Mr. Salmon has thus noted, in V. 675., on the egg of the 

 cuckoo, as compared with that of the pied wagtail. It is 

 " much superior in size, considerably darker, about the size 

 of that of the skylark, but more of an oval shape. The dif- 

 ference is so great between the eggs of the cuckoo and those 

 of the pied wagtail, that I am quite certain that any person 

 with common observation would instantly detect it." Mr. 

 Turner's friend noticed that the cuckoo-eggs, as they proved, 

 were larger than the wagtail's, (p. 287.) Professor Rennie 

 has described, in his Mont. Orn. Diet., p. 193., the egg of the 

 cuckoo as " small, rounded, and greenish, yellowish, bluish, 

 or greyish white, and always blotched, not marbled, with 

 olive or ash colour, being about the size of a house-sparrow's, 

 and very like it in colour." Professor Brande has remarked, 

 that " the cuckoo very commonly selects the nest of the 

 hedge-sparrow, a spotted brown egg among bright blue." 



Mr. Hewitson, in his British Oology, t. lv., has figured the 

 eggs of the cuckoo, and, in a description appended, has this 

 remark among others: — " The eggs of the cuckoo are found in 

 the nests of several species of small birds. It, however, seems in- 

 stinctively to prefer those, the eggs of which most nearly resem- 

 ble its own. [The remarks adduced above will serve to test the 

 accuracy of this view.] Among these are the several species 

 of lark [Mr. Hewitson includes the rock pipits, and, perhaps, 

 all the pipits, among these], the pied wagtail, and the grass- 

 hopper warbler : it most frequently, however, makes choice 

 of that of the titlark, which is common on those open heaths, 

 its favourite resort. [In certain neighbourhoods, not heathy, 

 it may be that it oftener chooses the pied wagtail's nest : see 

 p. 300.] The egg, which is remarkable for its small size, is 

 thus, together with its colour, admirably fitted for the decep- 



