Pallas’s Leaf WarblerPhylloscopus proregulus, Jiangsu, China, May. Pallas’s Leaf Warbler is one of the Big 5 leaf warblers of Shanghai. The species passes through the city-province on migration and can be found in winter there. Northeast China and the Russian Far East are part of the breeding range of this East Asian warbler. (Craig Brelsford)
PALLAS’S LEAF WARBLER: IDENTIFICATION
Pallas’s Leaf WarblerPhylloscopus proregulus breeds across southern Siberia and Mongolia to Sakhalin Island; in China in Heilongjiang and eastern Jilin. Winters eastern China south of Yangtze River to Southeast Asia. Common passage migrant and winter visitor Shanghai. Breeds in coniferous forests, to 1700 m (5,580 ft.); on passage and in winter lower and in more varied woodland habitat, including city parks. Very active, constantly moving from perch to perch; often hovers, recalling Goldcrest, with which it is sometimes seen. Tiny, large-headed, short-tailed. The eponym of the Pallas’s Leaf Warbler Complex, of which it is the most brightly colored and boldly marked member. Has well-defined, pale-yellow central crown-stripe equally distinct throughout length, dark olive-grey lateral crown-stripes (greener or even yellowish in front), bold yellow supercilium (turning whitish posteriorly), and long, brownish-black eye-stripes that may be hooked at rear. Wings blackish-grey with prominent yellow wingbars on median and greater coverts and dark bar at base of secondaries. Tertials blackish with white fringing; also remiges (and, to lesser degree, tail feathers) tipped white when fresh. Pale yellow rump conspicuous when bird hovers, contrasting with olive-green mantle and uppertail coverts. Short, dark brownish-grey tail, lacking white. Underparts greyish-white. Pallas’s Leaf Warbler has brighter lemon-yellow supercilium and coronal crown stripe, bolder head pattern, and greener mantle, yellower wingbars, and whiter underparts than Lemon-rumped Warbler P. chloronotus, Gansu Leaf WarblerP. kansuensis, and Sichuan Leaf WarblerP. forresti. Small, delicate bill brownish-black with orange base to lower mandible. Feet orange-brown, usually darker than Yellow-browed WarblerP. inornatus. Pallas’s is also smaller and more compact and has larger and rounder head, shorter bill and tail, darker and broader eye-stripe, and broader supercilium than Yellow-browed Warbler. Song a loud, melodious series of trills and whistles, sometimes lasting several minutes, and delivered from concealed perch in canopy. Call a soft, nasal, distinctly up-turned “dweet,” repeated incessantly. — Craig Brelsford
On Tuesday I arrived at Cape Nanhui too late to see Crow-billed Drongo. My partners Kai Pflug and Elaine Du and I made the fateful decision to cover Hengsha Island in the morning. The alluvial island at the mouth of the Yangtze was decidedly humdrum, with Far Eastern Curlew out on the mud along with 2 Sanderling and a Ruddy Turnstone. The huge new tree plantation on the island failed to deliver any forest birds beyond a single Asian Brown Flycatcher. There was a good count (17) of Richard’s Pipit.
We arrived at Cape Nanhui and found kaca, who mentioned an unusual drongo he had seen that morning. We kept our eyes peeled for dark drongos, finding none. Our Nanhui harvest was limited to expected October birds such as Grey-backed Thrush (6) and Eyebrowed Thrush (2). Asian Brown Flycatcher (26) seemed to be on every tree.
All of Shanghai’s Big 5 Leaf Warblers were present: Pallas’s Leaf Warbler (1), Yellow-browed Warbler (1), Arctic-type Warbler (2), Pale-legged/Sakhalin Leaf Warbler (7), and Eastern Crowned Warbler (2).