THE SIBERIAN CHIFFCHAFF. 303 



coverts bright pale lemon-yellow ; wings and tail much as in Ph. c. 

 collybita but with narrow fringes of olive-green on outer webs ; 

 wing-coverts brown narrowly tipped and fringed olive-green. 

 Summer. As winter but still browner with usually no trace of 

 green on upper -parts and scarcely any on wings and tail. Moult 

 as in Ph. c. abietinus. 



Nestling. (Not examined.) 



Juvenile. Like adult summer, but upper -parts rather paler 

 brown and without any green tinge. 



Measurements and structure. $ wing 56-66 mm., tail 45-53, 

 tarsus 17.5-21, bill from skull 9.5-10.5 (12 measured). $ wing 

 54-61. Primaries : 1st 5-8 mm. longer than longest primary- 

 covert, 4th and 5th longest, 3rd sometimes as long but usually 

 1 mm. shorter, 6th .5-2 shorter, 7th 3-5 shorter, 2nd usually 

 between 8th and 9th or equal to 8th, only occasionally longer 

 than 8th ; 2nd is thus usually shorter proportionately and 6th 

 and 7th are usually a shade longer proportionately than in Ph. c. 

 collybita. Other structure as in Ph. c. collybita. 



Soft parts. As in Ph. c. collybita but legs and feet usually 

 blacker 



CHARACTERS. Easily distinguished from both Ph. c. collybita and 

 Ph c. abietinus by absence of yellow in under -parts, pale buffish- 

 brown sides of breast and flanks, brown (not olive) upper -parts. 



FIELD -CHARACTERS .--Distinguishable from Ph. c. collybita by its 

 white under -parts, which are almost suggestive of Lesser White- 

 throat, and at once mark it out as distinct from any common 

 British Phylloscopi. The single bird observed by me during a 

 fortnight in Kent in December spent all its time ceaselessly flitting 

 along some hedge-rows in a deep gully, and in its behaviour showed 

 no peculiarity to distinguish it from allied species. Note, fairly 

 frequently uttered, was single, a good deal more plaintive than 

 that of Chiffchaff or Willow-Wren, and perhaps nearest to the 

 single note sometimes uttered by Coal-Tit ; its difference from 

 notes of the common species is so marked as to attract attention 

 at once (H. G. Alexander). 



BREEDING-HABITS. Nests often in willow and alder thickets 

 or in rank vegetation, at times also in flood refuse stranded in bushes 

 Nest. Similar to that of typical race, warmly lined with feathers. 

 Eggs. Also similar in type, but markings sometimes red instead 

 of purple. Clutch 5-9, probably 6-7 normally. Average of 80 

 eggs 15x11.9 mm. Breeding -season. May and June in the Altai, 

 but end of June and early July in north Siberia. 



FOOD. Insects, chiefly diptera (mosquitoes) during breeding- 

 season. 



DISTRIBUTION, England. One watched Tunbridge Wells (Kent 



