0 the yellow-browed warbler (phylloscopus inornatus) is a leaf warbler (family phylloscopidae) which breeds in temperate asia .
1  this warbler is strongly migratory and winters mainly in tropical southeast asia , but also in small numbers in western europe .
2  like the rest of phylloscopidae , it was formerly included in the old world warbler assemblage .
3 it was formerly considered to comprise three subspecies , but p .
4  i .
5  humei and p .
6  i .
7  mandellii are now split as a separate species , hume's leaf warbler p .
8  humei , leaving p .
9  inornatus monotypic .
10  the two sister species differ slightly but consistently in morphology , bioacoustics , and molecular characters .
11  before the species was split , the names yellow-browed willow warbler and inornate warbler were used by a few authors .
12  the genus name phylloscopus is from ancient greek phullon , "leaf", and skopos , "seeker" (from skopeo , "to watch") .
13  the specific inornatus is latin for "plain" .
14 this is one of the smaller old world warblers , at 9.511 cm long and weighing 49 g distinctly smaller than a chiffchaff but slightly larger than pallas's warbler .
15  like many other leaf warblers , it has overall greenish upperparts and white underparts .
16  it also has prominent double wing bars formed by yellowish-white tips to the wing covert feathers (a long bar on the greater coverts and a short bar on the median coverts), yellow-margined tertial feathers , and long yellow supercilium .
17  some individuals also have a faint paler green central crown stripe though many do not show this .
18 it is not shy , but its arboreal life style makes it difficult to observe .
19  it is almost constantly in motion .
20  its song is a high pitched medley of whistles; the call is piercing , often disyllabic "tseeweest", strikingly loud for the bird's small size .
21  the only real possibility of confusion is with the similar-looking hume's leaf warbler (p .
22  humei), which in the limited area of overlap has duller colours , a faint second wing bar and dark legs and lower mandible .
23  their songs and calls are clearly distinct , with hume's having a more chirping "chwee" call .
24  it can easily be distinguished from pallas's warbler as it does not have the a conspicuous yellow central crown stripe and rump patch shown that species .
25 like most warblers , it is insectivorous .
26  the nest is built in dense vegetation often at the base of a tree or old stump; two to four (occasionally more) eggs are laid , hatching after 1114 days , with the chicks fledging when 1213 days old .
27 this is an abundant bird of lowland and montane forests and woodlands; particularly in winter it may also be found in more open woods .
28  its breeding range extends from just west of the ural mountains eastwards to eastern siberia , mongolia and northeastern china .
29  its winter habitat is lowland broadleaf or coniferous forest , from west bengal and assam in northeastern india east through southern china to taiwan , and south to the malay peninsula .
30  in summer , it occurs at altitudes of up to 2,440 m , and in winter , up to 1,525 m .
31 the european breeding population west of the urals has increased westwards in recent decades; in 1950 it was described as 'fairly scarce', but 'locally abundant' with 45,00046,000 pairs in 1990.small numbers , most likely from the western end of the breeding range , regularly winter in western europe .
32  these arrive in great britain in late september and october after a 3,0003,500 km migration from the urals , a markedly shorter distance than the 5,5006,000 km they would need to fly to reach the normal wintering areas in southeastern asia .
33  exact numbers in this population are unknown , but typically several hundred are found arriving in great britain each autumn; given their unobtrusive behaviour , this is probably only a fraction of the total .
34  in the past widely considered to be vagrants , these birds are now thought to be undertaking a normal regular migration , able to take advantage of the mild oceanic climate winters on the western fringes of europe for wintering .
35 a common species in most of its wide range , the yellow-browed warbler is not considered threatened by the iucn .
36 hume's leaf warbler overlaps its breeding range with yellow-browed warbler in the western sayan mountains , but the species apparently do not hybridise .
37  their lineages diverged roughly 2.5 million years ago .
