The Oologists' Record^ September i, 1921. A 9 



9, Hay Hill, 



Berkeley SyuAKE, W. i. 

 August loth, 1921. 



Dear Sir, 



Mr. G. J. Scholey has most kindly afforded me an opportunity 

 of inspecting the series of eight Cuckoos' eggs taken in five Pied 

 Wagtails' nests, during the. past season, and he has also personally 

 shown me the nesting sites referred to. 



The enquiry which Mr. Scholey is so enthusiastically pursuing is 

 lull (jf interest. Although it is of course impossible delinitely to 

 declare that the two Cuckoos which on three occasions this season 

 laid in the same Wagtail's nest are mother and daughter, there is 

 no doubt that the character of the eggs, as regards shape, size and 

 markings, though differing in colour, lend support to that belief. 

 Mr. Schole}^ declares emphaticall}' that each of the three Wagtails' 

 nests in which the two Cuckoos laid received both Cuckoos' eggs 

 on the same days, viz., the 4th, nth, and 20th June respectively. 



It is to my mind an astounding coincidence that on each of the 

 three occasions both Cuckoos should lay on the same day, and 

 that too when the interval of time between the laying in each nest 

 was not less than a week. One is almost forced to the conclusion 

 that there was some collusion or co-operation between the two 

 female Cuckoos. 



As a result of my own intimate study of the Cuckoo's habits 

 during the past four seasons, I have formed the conclusion that sooner 

 or later one female Cuckoo will dominate a given territory. By this 

 I mean that I should not expect to find in two consecutive seasons a 

 run of several eggs in any given area from two different Cuckoos, 

 laid in nests of the same species of fosterer. I feel sure that the 

 tendency is for each individual female to more or less monopolise 

 her natural fosterers in her territor}-, driving out any other females 

 desirous of depositing their eggs in the same nests. This aspect 

 of the fascinating Cuckoo question, let alone the whole field of 

 research into the habits of Cu cuius ca/iorus, is too big a subject to 

 go into more fully on this occasion. 



I wish, however, to pay tribute to the painstaking study which 

 Mr. G. J. Scholey is making, and I hope that he will make every 

 endeavour to find every Wagtail's nest in his quarry next season. 



