95 [Vol. xlii. 



2, Do Cuckoos invariably deposit their eggs in the nest of 

 the same species of foster-parent ? 



The answer to this will also be in the affirmative, for we 

 may now accept it as proved that Cuckoos do normally always 

 select the same species of fosterer for their eggs ; at the same 

 time we must be careful to remember that all Cuckoos have 

 not had the same care and forethought bestowed upon them 

 that Mr. Chance's Cuckoo had. Many Cuckoos meet with 

 difficulties which were smoothed away for his bird. Even 

 in this case, however, we find that on one occasion when 

 there was no Meadow-Pipit's nest available, she laid in a 

 Tree-Pipit's, and on another occasion was so hard pressed 

 that she actually deposited an egg in one made by human 

 hands. Now, no one will contend that a bird of the intelli- 

 gence displayed by Mr. Chance's Cuckoo (an intelligence 

 probably common to all Cuckoos) could ever have been 

 deceived into believing such to be a Meadow-Pipit's self- 

 made nest. Under ordinary circumstances, it must often 

 happen that a Cuckoo can find no nest of its normal fosterer 

 within its own special area. Two solutions only are then 

 possible : it must leave this area and hunt for a nest of the 

 fosterer elsewhere, or it must be content to deposit its egg 

 in some other bird's nest. The latter is, I think, the usual, 

 but not the invariable, course adopted. 



Referring to the eggs taken by Mr. Scholey (Box. No. 5), 

 you will see that in one case the Cuckoo placed her first two 

 eggs in the nests of Hedge-Sparrows, built practically on 

 the same ground as that she covered for Reed-Warblers' 

 nests, whilst the remaining five found that year were all in 

 the latter birds' nests. The following year, 1920, all I'd eggs 

 were taken from Peed-Warblers' nests, as were the still 

 larger number taken in 1921. Another Cuckoo, on an 

 adjacent ground, we find putting her first egg in the nest of 

 a Yellow-Hammer and her second in that of a Meadow- Pipit. 

 In yet another case we have eggs of a third Cuckoo placed 

 the same year in the nests of a Sedge- Warbler, of a Linnet, 

 and, finally, in a E,eed-Warbler's, all three nests being close 

 together. After the third egg was deposited, this Cuckoo 

 seems to have been driven away by another, tlie latter 



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