302 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



mantle, which are greyish-brown with scarcely a tinge of green ; 

 ear -coverts and sides of neck are also more greyish-brown with 

 only a tinge of yellow ; under-parts are whiter, less buff and yellow. 

 Moults as in Ph. c. collybita but often autumn moult not complete 

 before Oct. 



Measurements and structure. — (^ wing 62-66 mm., tail 50-52. 

 tarsus 19-21, bill from skull 9.5-11 (20 measured). $ wing 56-67 

 Wing longer than in Ph. c. collybita but largest individuals of latter 

 equal smallest of Ph. c. abietinus. Tail averages longer. Other 

 structure as in Ph. c. collybita. 



Breeding-habits. — Similar to those of the British breeding race, 

 but according to CoUett the clutch usually consists of 8 eggs, 

 laid during May or early in June. Average of 43 eggs, 15.1 X 

 12.0 mm. 



Food. — Presumably similar to that of typical race. 



Distribution. — England. — One, a female, St. Catherine's Light 

 (Isle of Wight), April 15, 1907 {ut supra). Scotland. — Fair Isle 

 (Shetlands) regular spring and autumn passage-migrant (W. E. 

 Clarke, Studies in Migration, II., p. 131). St. Kilda, one Oct. 11, 

 1911 {id. t.c, p. 214). Isle of May (Forth) a good many Sept .-Oct.. 

 1912, one Sept. 30, and others Oct. 1913, two Nov. 1914 (E. V. 

 Baxter and L. J. Rintoul, Scot. Nat., 1913, p. 52, 1914, pp. 108-9, 

 Ibis, 1918, p. 269). Auskerry (Orkneys) small numbers, Sept., 

 Oct., 1913 (W. E. Clarke, Scot. Nat., 1914, p. 8). Probably regular 

 passage-migrant, jaerhaps only in small numbers, but undoubtedly 

 overlooked owing to difficulty of identification. 



Distribution. — Abroad. — Generally north and east Europe, but 

 difficult to distinguish, therefore distribution not well known, and 

 requiring further study. In winter known to occur in southern 

 Arabia and Egypt. 



125. Phylloscopus collybita tristis Blyth — THE SIBERIAN 

 CHIFFCHAFF. 



Phylloscopus tristis Blyth, Journ. As. Soc. Bengal, xn, p. 966 (1843- 



Calcutta). 



Phylloscopus tristis, Clarke, Ann. Scot. Nat Hist., 1907, p. 15 ; id., Bull. 



B.O.C., XIX, p. 18 ; Saunders, Brit. B., i, p. 8. 



Description (Plate 11). — Adult. Winter.— hike Ph. c. collybita but 

 upper-parts brown with only a tinge of green on mantle and rump 

 (in some examples this green tinge is absent) ; stripe from base 

 of bill over eye and orbital ring wlnte or creamy-white ; ear- 

 coverts, sides of neck, sides of breast and flanks pale buffish- 

 brown ; rest of under-parts white washed pale buffish-brown 

 with no yellow as in Ph. c. collybita ; axillaries and under wing- 



