Phyllopneuste borealis Blasius, Naumannia (1858), 313.
Phylloscopus borealis Seebohm, Cat. Birds Brit. Mus. (1881), 5,
40; Whitehead, Ibis (1899), 210 (migration).
Acanthopneuste borealis Oates, Fauna Brit. Ind. Bds. (1889), 1,
412; Sharpe, Hand-List (1903), 4, 216; Oates and Reid, Cat. Birds'
Eggs (1905), 4, 227; McGregor and Worcester, Hand-List (1906), 90.
Balabac (Everett); Bantayan (McGregor); Basilan (McGregor); Bohol
(McGregor); Calamianes (Bourns & Worcester, McGregor); Calayan
(McGregor); Caluya (Porter); Cebu (McGregor); Cuyo (McGregor);
Fuga (McGregor); Guimaras (Bourns & Worcester); Leyte (Everett);
Lubang (McGregor); Luzon (Everett, Whitehead, McGregor, Bartsch);
Maestre de Campo (McGregor & Worcester); Masbate (Steere Exp.);
Marinduque (Steere Exp.); Mindanao (Everett, Steere Exp.,
Celestino); Mindoro (Bourns & Worcester, Whitehead, McGregor);
Negros (Whitehead); Palawan (Whitehead, Platen, Steere Exp.,
Bourns & Worcester); Panay (Steere Exp.); Polillo (McGregor);
Romblon (Bourns & Worcester); Samar (Bourns & Worcester); Sibuyan
(Bourns & Worcester); Siquijor (Celestino); Tablas (Bourns &
Worcester); Ticao (McGregor); Verde (McGregor). Northern Europe,
northern Asia, Alaska, Commander Islands; in winter to China,
Formosa, Indo-Chinese provinces, Malay Peninsula, and Borneo.
"Coloration.--Upper plumage olive-green, lighter on the rump; wings
brown, the outer webs edged with olive-green; wing-coverts brown on
the inner and olive-green on the outer webs; the median and greater
coverts with yellowish white tips forming two bars; tail brown, the
outer webs edged with olive-green; a broad and well-defined eye-streak,
reaching to the nape, yellowish white; lores brown; ear-coverts olive
mingled with yellowish; under plumage white, suffused with yellow;
under wing-coverts and axillars pale yellow.
"As the summer goes on the wing-bars get worn away and the upper one is
sometimes absent. The lower plumage gets whiter and the upper plumage
duller. After the autumn molt the wing-bars are very conspicuous and
the under parts become suffused with deeper yellow.
"Upper mandible dark brown, the edges and tip yellow; gape and basal
half of the lower mandible orange-yellow, terminal half dusky; mouth
bright orange-yellow; iris dark brown; legs flesh-color tinged with
yellow; claws yellowish horn-color. Length, 122; tail, 51; wing, 68.5;
tarsus, 20; bill from gape, 17; the second primary is intermediate
in length between the fifth and sixth, and is sometimes equal to the
sixth; the first primary is very small, measuring from 7.6 to 11.4
in length." (Oates.)
The arctic willow warbler is the commonest species of the genus
and is found in the Philippines during the winter months. Most of
the specimens taken at this time have the under parts but faintly
suffused with yellow and in this plumage the wing-bar is indicated by
light spots on the outer webs of some of the greater coverts. This
plainly colored species is usually seen flitting among the branches
of forest trees and at such heights that it can not be distinguished
from other species of similar habits.