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The eggs of the Cuckoo vary considerably in coloration, as may be supposed from eggs ot 

 this species having been found to resemble those of various foster-parents. The usual form of 

 egg is greyish white marked with greenish buff, not unlike some eggs of the common White- 

 throat ; but I have some which are not unlike a large Wagtail's egg, and others which, on a light 

 grey ground, are finely mottled or spotted with pale reddish ; and the egg in my collection, taken 

 with those of the Tree-Creepers, is very pale greyish with a faint greenish tinge, sparingly 

 blotched with pale greenish buff, and is rather above the usual run of Cuckoo's eggs in size ; for, 

 as a rule, the eggs of this species are very small in comparison with the size of the bird, averaging 

 about -f^ by f $ inch. I may here remark that I have seen a Cuckoo's egg of a very peculiar 

 shade of bluish green. Messrs. Degland and Gerbe state that they have two pure white in 

 colour ; and Mr. K. Collett writes to me that he took one of a uniform bluish white colour witli 

 three eggs of Pratincola rubetra. 



Mr. H. Seebohm, when in Hanover a short time ago, examined the splendid series of Cuckoo's 

 eggs in the collection of Mr. Pralle, late of Hildesheim, in which are some most peculiar varieties. 

 Mr. Seebohm has lent me his note-book, in which are copious notes respecting this collection, 

 from which I extract the following, viz. ':— " In this collection are twelve blue Cuckoo's eggs, 

 some uniform, unspotted, whereas others have faint spots, like fly-spots, here and there. The first 

 of these was in a nest of Saxicola stapazina, L. (Saxicola aurita auctt.), and is blue, with a few 

 Bunting-like streaks ; no. 2 was found with four eggs of Ligurinus chloris, and is blue, with a few 

 fly-spots ; nos. 3 and 4 are unspotted blue, and are each with five eggs of Phylloscopus sibilatrix ; 

 no. 5 is with three eggs of Buticilla plioenicurus, and is also unspotted blue ; no. 6 is with five 

 eggs of B. pliwnicurus, and no. 7 with three eggs of the same species, this latter egg being blue, 

 with a few faint fly-spots; nos. 8, 9, 10, 11, 12 are all blue, with traces of spots, and are all with 

 four or six eggs of Buticilla plioenicurus, except the last, which was found with only one egg of 

 that species. Amongst the other Cuckoo's eggs in the collection are several of considerable 

 interest, but none in the nests of any other species beyond those in the above list ; but I may 

 remark that there are nine each with from one to five eggs of Lanius collurio" 



The young Cuckoo almost as soon as it is hatched commences to evict the eggs or young 

 of the foster-parent from the nest, and soon makes itself the sole tenant. In cases where two 

 Cuckoo's eggs have been deposited in the same nest, and both have hatched out, a contest arises 

 between the two birds, which ends by the summary eviction of the weaker of the two ; hence 

 when a Cuckoo has grown to any size it is always found to be the sole occupant of the nest. 

 Dr. Jenner, the discoverer of vaccination, appears to have been the first to observe and record 

 (in the 'Philosophical Transactions' for 1788) this fact. He states that he found the nest of a 

 Hedge-Sparrow containing an egg of the Cuckoo and three of the Hedge-Sparrow, but the day 

 following a young Cuckoo and a young Hedge-Sparrow, two of the eggs having disappeared : he 

 " saw the young Cuckoo, though so late hatched, in the act of turning out the young Hedge- 

 Sparrow. The little animal, with the assistance of its rump and wings, contrived to get the bird 

 upon its back, and making a lodgment for its burden by elevating its elbows, clambered back- 

 wards with it up the side of the nest till it reached the top, where, resting for a moment, it 

 threw off its load with a jerk, and quite disengaged it from the nest. It remained in this situation 



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