38 Birdwatch•October 2017 http://www.birdguides.com/birdwatch
IDENTIFICATION
BASIC PRINCIPLES
T
here can be few
more eagerly awaited
October birds than the
wing-barred Phylloscopus or
leaf warblers. Three species –
Yellow-browed, Hume’s Leaf
and Pallas’s Warblers – are
among the most delightful
birds on the British list:
tiny, hyperactive and jewel-
like. They are not the only
options, however. The much
rarer Eastern Crowned and
Pale-legged Leaf Warblers,
both recent additions to the
British list, are also possible
in October.Yellow-browed Warbler
This species has a large and
northerly breeding range
across Siberia, reaching as far
west as the northern Urals. It
winters throughout southern
China and South-East Asia.
There were relatively few
British records until the
1960s. Since then, however,
there has been a massive
increase in occurrences, with
many hundreds reported
in most years and multiple
arrivals now routine on the
Northern Isles, the east coast
and Scilly, all locations where
this can be the commonest
warbler species at times.
It occurs earlier than
Pallas’s Warbler, normally
from mid-September, but
arrivals can continue into
November, with a peak in
late September and early
October. In recent years,
a few have also wintered,
mainly in the South-West,
and there have been a
number of spring records.
Slightly larger than
Pallas’s Warbler, it is still a
tiny bird, though a little less
compact, large headed and
short tailed, and it lacks the
sustained hovering capability
of Pallas’s. It is also bright
and has a slightly weaker face
pattern, a more yellowish
cream supercilium, a paler
crown with no central stripe
(although a weak pale centreEastern Crowned
Warbler
This slightly larger species
has an extreme Far Eastern
distribution, breeding in
Transbaikalia, the Russian
Far East, Korea and Japan. It
winters in southern Thailand
and Malaysia.
The fi rst British record was
in 2009, since when a further
three have occurred, all in
October. There are no Irish
records.
It is perhaps most similar to
Arctic Warbler, but is brighter
green above with narrow
double wing-bars, plain
tertials, a yellowish wash to
the undertail coverts, extensive
orange in the lower mandible
and, most importantly, a pale
central crown stripe, most
obvious from behind.
It rarely calls, particularly
so during its few British stays,
but can utter a strident chiu, a
quieter phit phit or a nasal dweee.Pale-legged Leaf
Warbler
Pale-legged Leaf Warbler
breeds even farther east than
Eastern Crowned Warbler –
in the Russian Far East and
North Korea – and winters in
South-East Asia.
The only confi rmed British
record was a bird found dead
on St Agnes, Scilly, in October
2016, but another example- either of this species or the
near-identical Sakhalin Leaf
Warbler (breeding in Sakhalin
and Japan, and a recent split) - was on Portland, Dorset, in
October 2012.
Pale-legged Leaf Warbler is
a dark mossy green above, with
a contrasting greyish forehead,
crown and nape (with no
central stripe). There are
narrow double wing-bars and
the tertials are plain. The legs
are a very pale pink, but its
most notable features might be
its neurotic, rather Dusky
Warbler-like behaviour and
distinctive, high-pitched,
insistent zink call. ■
reminiscent of Greenish
Warbler, and a down-slurred
swee-oo with a harsh, almost
House Sparrow-like, quality.Pallas’s Warbler
Pallas’s Warbler breeds across
southern Siberia, and winters
in southern China and South-
East Asia.
It was a near-mythical
rarity in Britain before the
1980s, but since then there
has been a remarkable
upsurge in records. It is
now an expected feature
of late autumn, with some
years seeing more than 200
records. It is found from
early October through to late
November, the fi rst arrivals
often on the Northern Isles,
with later birds mainly along
the south coast and in the
South-West. Mostly, however,
this is a bird of the east coast.
Pallas’s Warbler is a truly
tiny species, compact, large
headed and short tailed, barely
bigger than a Goldcrest but
incomparably brighter. A
typical view is that of a tiny
jewel of a bird, bright green
above and whitish below, and
adorned with broad, bright
yellow supercilia bulging before
the eye, a strong dark eyestripe,
and dark crown sides with a
sharply defi ned yellow central
stripe. It boasts broad, double
yellow wing-bars, white tertial
edges and a neat ‘postage
stamp’ of a yellow rump.
Pallas’s Warblers habitually
hover, picking insects o the
underside of leaves, and they
can hang upside down like a
tit, too.
Its call is quiet and easily
missed: a soft, slightly fi nch-
like chewit.may be present) and no pale
rump. The creamy-yellow
wing-bars and white tertial
edges are, however, broad and
prominent.
Unlike its congener, it is very
vocal and often fi rst located by
its distinctive call: a quite loud,
high-pitched, penetrating and
rising tse-weee.Hume’s Leaf Warbler
A southern montane
counterpart of Yellow-browed
Warbler, Hume’s breeds in
Central Asia and winters
in the Indian subcontinent.
Previously regarded as a
subspecies of Yellow-browed,
its distinct morphology and
vocalisations are now better
understood.
This is by far the rarest of
the regular tiny leaf warblers
in Britain, with 139 records to
the end of 2015, but as with
the other species, there is an
upward trend. This is a bird of
late autumn, occurring in late
October and November (at the
same time as Pallas’s Warbler).
The east coast has amassed the
lion’s share of records. A few
individuals have overwintered.
In size and structure, this
species is essentially identical
to Yellow-browed Warbler.
However, its plumage is duller,
more grey-green and less
bright above, and ‘dirtier’ or
more ‘sullied looking’ below.
Its face pattern is blander and
may be su used with bu ,
while its wing-bars and tertial
edges are less boldly defi ned
and contrasting. Its median
covert wing-bar may be almost
absent. The bill and legs are
predominantly dark.
It has two call types: a
cheery, rising che-wee, slightly❝
Yellow-browed, Hume’s Leaf
and Pallas’s Warblers are among
the most delightful birds on the
British list
❞
1710 p37-43 ID photo guide leaf warblers v3.indd 38 13/09/2017 17:13:26