144 BRITISH BIRDS. [vol. xiii. 



and there just a trace of pale brown in the edging. The bill 

 was grey, tipped with black, and the legs light grey, with the 

 feet black. 



Dr. Hartert and I examined the skins in the Tring Museum, 

 comparing them with the photograph, and there seems little 

 doubt that the visitor to the reservoirs was a Long-tailed 

 Skua {Stercorarms longicaudus) . 



While I watched the bird it caught several small fish, and 

 also pecked at the remains of a half-pound roach which was 

 lying on the bank ; whether it caught the latter I could not 

 say, as this might have been left there by an angler. The 

 Skua showed no signs of fear, and even after some small 

 boys had pelted it with stones it returned to its favourite 

 corner, remaining there until August 30th. 0. G. Pike. 



LETTER. 



WEIGHTS OF CUCKOOS' EGGS. 

 To the Editors of British Birds. 



Sirs, — The Rev. F. C. R. Jourdain is probably quite correct in his 

 identification of the Chaffinch's egg mentioned in the August issue of 

 British Birds {antea, p. 81) ; it would, however, be dangerous to assume 

 that an egg could not be a Cuckoo's because it weighs only 153 mg. 



The average weight for Cuckoos' given, 231 mg., is evidently Rey's 

 weight for 710 eggs, all of which we may safely assume were of Con- 

 tinental origin ; my average weight for 54 British eggs is 224.3 rng., 

 which is considerably lighter for the average than Continental eggs. 



The maximum weight given in Oologia Universalis Palcsarctica, 

 George Krause, is 320 mg. and the minimum 150 mg., the average given 

 in Oologia Neerlandica, Lechner, is 231 mg., which is also evidently 

 Rey's average. 



My maximum weight is 299 mg., and the minimum 151 mg., below 

 the maximum Continental, and i mg. only above the minimum. 



Weights and measurements are of considerable value and interest 

 in identification when taken in conjunction with general characteristics. 

 The latter point apparently influenced Mr. Jourdain in his decision. 



Croydon. P. F. Bunyard. 



[The weight was, of course, taken in conjunction with the size, 

 texture of shell and other characteristics. Lechner gives no informa- 

 tion as to the number of eggs weighed, and Krause's figures are similarly 

 defective. Many of Rey's eggs were of British origin, as may be seen 

 by reference to Altes und Neues. Personally I am of opinion that verj' 

 strong corroborative evidence is necessary in the case of all supposed 

 Cuckoos' eggs below 160 mg. in weight. — F. C. R. Jourdain.] 



