Warbler - British Trust for Ornithology

32 ACROCEPHALU.) BISTRIGICEPS
sides ofbreast and flanks buff Fresh autumn dress is more rufous
above and deeper buff below than in spring.
Occurs in tall grasses and brush along roadsides, so is not
restricted to marshes and rivers.
Ageing. 1st-winter birds are like autumn adults after the postnuptial
body moult, but the latter have remiges and rectrices
bleached and worn.
Colours ofsoft parts. Bill: upper mandible black, lower yellowish
or flesh. Legs: brownish-olive or plumbeous-f1esh, soles greenishyellow.
Mouth: yellow. Iris: greyish-hazel or dark brown.
Measurements. Wing, 60 50-58, CjlCjl 50-56. Tail, 33 44-52, CjlCjl
42-5 I. Bill, 12-15. Tarsus, 19-23. See Tables on pages 66, 68.
Tail rounded, 9-13. Wing/tail ratio of 41 bistrigiceps 81-96 (cr
tangorum).
Weight. Shaw (1936) gives average of16 30',9.4 (8-II) gm.; 8 ¥¥
8 (7-10) gm.
Wing-formula (pp. ascendant). Emarginated 3rd-5th. Long 1st p.
3-7+ p.c.
Wing-point, 3rd = 4th, occasionally = 5th; otherwise 5th,
!-I; 6th, 2-3; 7th, 3-6; 10th, 7-1O!.
2nd, 4-6, falls between 6th-8th (usually 6th-7th). Notch on
inner web 12-13 from tip, falls about middle of ss. Notch on
inner web of 3rd falls opposite tips of ss. Slight notch on inner
web of 4th falls opposite loth p. Longest tertial falls short of
loth p.
Moult (pp. descendant). Apparently a body-moult on the breeding-growld is
succeeded by wing and tail moult in winter quarters: I. C. T. Nisbet reports
a complete moult in first half of winter in MalavJ. A ¥ from Yezo, Japan,
13.ix.• is finishing pp. 8-9 and ss. 5-6, and one from 24.X. is in fresh dress. Birds
of the typical race in winter quarters are in fresh plumage froll1 November­
January but very worn by April-Mav.
Distribution. N.E. Mongolia and S.l:. :>lben,l tu Sakh ..diu anJ Japan, south to
N. China and lower Yangzte Valley Winters ".I:. CiUlla and InJo-ChincsL
countries west to S Burma
d