284 LETTERS. [vol.xiv. 



themselves proof that they are all the product of one female, and this 

 view is supported by the fact that other hen Cuckoos have made use 

 of the same nests on four occasions. 



With regard to the suggestion that the eggs were laid by two or 

 more closely related females, how are we to account for the fact that 

 the intervals between oviposition are so uniform ? Is it credible 

 that another female was present on the same ground, laying a precisely 

 similar egg, and invariably depositing it in a different nest, always on 

 a date when the first hen for some unaccountable reason failed to lay ? 

 As to the time occupied in laying and depositing the Cuckoo's egg in 

 the fosterer's nest, it is difficult to believe that five observers, all 

 simultaneously watching at various distances from 40 to 120 yards 

 and using powerful binoculars, could have been repeatedly deceived. 

 The alternative suggested is pure supposition unsupported by direct 

 evidence. Herbert Massey. 



Ivy Lea, Burnage, Didsbury, April nth, 1921. 



Sirs, — The suggestion first made by Newton, that similar eggs of 

 the Cuckoo from the same district might possibly be those of closely 

 related females (perhaps mother and daughter) seems to be mere 

 speculation, quite unsupported by proof. All the evidence points in 

 the opposite direction. When the territories of two or more female 

 Cuckoos overlap, it occasionally happens that the same fosterer is 

 victimized by more than one bird, but out of the large number of cases 

 of this kind, I have never known a single case in which there was 

 satisfactory proof that both eggs were laid by the same bird. It is 

 of course possible that an occasional lapse of memory occurs among 

 Cuckoos, as it certainly does among ornithologists. In the case of a 

 Cuckoo parasitic on a species like the Reed-Warbler it seems only 

 natural that the breeding territory should extend for some consider- 

 able distance along the banks of a suitable stream, while another female 

 parasitic on the Hedge-Sparrow or Redbreast might well have a much 

 more compact and circumscribed territory. Even supposing that a 

 fosterer's nest was pointed out to Mr. Chance by one of his assistants, 

 a few minutes' watching would settle the point as to whether it was 

 occupied by the parents or not, and the impossibility of providing a 

 Cuckoo's egg of exactly required type to order, on a date when the 

 Cuckoo under observation had for some unforeseen reason failed to 

 lay, is manifest to anyone who has given the least attention to the 

 subject. F. C. R. Jourdain. 



LIFTING AND WEIGHT-CARRYING POWER OF GOLDEN 



EAGLES. 



To the Editors of British Bird?. 



Sirs, — From time to time discussions arise on this question. It 

 would be interesting to learn if any of your readers have had personal 

 experience, or obtained authentic records of actual weights lifted and 

 carried by Golden Eagles. In a recent letter to The Times the writer, 

 Mr. L. Ropner, of Stockton, states that whilst fishing on Loch Shiel, 

 he saw an Eagle swoop, take up a fawn, and glide down the mountain 

 side for about half a mile. G. Witherington. 



19, Sumner Place, S.W.7. 



