Limestone Leaf Warbler Phylloscopus calciatilis Scientific name definitions

10–11 cm. A medium-sized leaf-warbler with yellow and black headstripes and yellow underparts . Lateral crownstripe blackish throughout length, median crownstripe and supercilium greenish-yellow, eyestripe blackish; cheek and ear-coverts yellow with greenish tinge, contrasting narrow yellow crescent beneath lower half of eye; upperparts rather bright greyish-green, brighter on rump and uppertail-coverts; median and greater upperwing-coverts brownish-grey, narrowly edged greyish-green, outer five greater coverts with broad yellowish-white tips (forming wingbar), outer two medians with narrow pale tips (indistinct short wingbar); flight-feathers and tail dark brown-grey with olive-green to yellow-olive outer margins; throat and underparts bright yellow, green tinge on sides, underwing-coverts pale yellow; iris dark grey-brown; upper mandible mostly blackish, cutting edges and lower mandible rather pale orange; legs light greyish-buff. Differs from P. cantator in yellow (not white) belly; probably indistinguishable in plumage from P. ricketti. Sexes similar. Juvenile resembles adult, but less intensely yellow below, and tips of greater coverts whiter.

Limestone karst regions of N & C Vietnam and N & C Laos, extending also into karst areas in extreme S China (Guangxi).

Forest on low limestone karst mountains, at c. 700–1200 m.

Song and call diagnostic. Song 7–9 softly whistled notes of varying pitch, duration and structure and on slightly falling scale, forming short verses (1·5–2 seconds long), mostly of simple upstrokes or downstrokes; fewer modulated notes than songs of P. ricketti and P. cantator, and with narrow frequency range. Call a short, soft “pi-tsu” or “pi-tsiu”, first syllable often inaudible; in short well-spaced series when bird alarmed.

Singing in mid-Feb in EC Laos (Hin Namno), and food-carrying male observed in mid-Apr in adjacent NC Vietnam (Phong Nha-Ke); at Nadi and Sayphou Loyang limestone areas, in NC Laos, frequent singing by apparently territory-holding individuals in May. No other information.

Not globally threatened (Least Concern). Restricted-range species: present in Annamese lowlands EBA. Not well known. Locally not rare. Recorded regularly, and is reasonably common in, protected areas; also common in areas where karstic mountain outcrops too steep, too sharply rocky and too dry for human settlement. Currently, there seems to be no threat to its habitat. Occurs in Hin Namno National Protected Area (Laos), in Cuc Phuong and Phong Nha-Ke National Parks (Vietnam), and Nonggang National Nature Reserve, and Chunxiu, Qinglongshan, Banli and Bangliang Nature Reserves (all in Guangxi, China).