306 Capt. H. Lynes on the Geographical Distribution 



plumage, the young bird just in its complete juvenile 

 dress. 



During the June visit there was less song, and young out 

 of the nest were frequent ; the main egg-laying period 

 would seem to have been about the last week of April. 



Now it seems to me that whether or no further experience 

 proves the doubtful character of the eggs to be a constant 

 one^ and still assuming that these Gibraltar-breeding birds 

 possess no external character of " form '^ * by which they 

 can be differentiated from examples of the typical race, the 

 peculiarity of song, which is constant, must have some 

 significance ; there must be some reason to account for 

 all these numerous Chiffchaffs producing alike the same 

 variation from the stereotyped "chiff-chaff" of the birds 

 breeding in our own northern latitudes f. 



It, at any rate, stamps that particular aggregate of indi- 

 viduals with a distinctive " habit " capable of recognition 

 by the .field-observer, and as such may prove useful in 

 the study of the important, and as jet little understood, 

 problems of migration and geographical distribution. 



The case of a sedentary race of the Chiffchaff to the 

 southward of Gibraltar has so important a bearing on the 

 subject, that I may perhaps be forgiven for recalling 

 the following facts with regard to the Canarian Chiffchaff, 

 P. c. canariensis Hartwig. 



In 1887 Capt. Savile Reid, having spent January to 

 April in Tenerife, wrote J as follows : — " Another bird quite 

 common in the lower region as well as in the forest region 

 .... extremely lively and abundant .... sorely puzzled by 

 the notes of this bird, which differ considerably from the well- 

 known ' chip-chop^ .... Canarian birds express their song 



* The word " form " used in tliis paper is intended to include 

 " colour." 



+ Dr. Hartert (Vog. pal. Fauna, i. p. 509) records an instance of a 

 Willow-Warbler in Germany singing- like a Chificliaff, but in that case 

 it seems to have been the idiosyncrasy of a single individual ; similar 

 observations have been recorded by Pasaler, Parrot and others. 



X ' Ibis,' 1887, pp. 431-2. 



