Eastern Crowned Warbler Phylloscopus coronatus 冕柳鶯
Category I. Passage migrant, uncommon in autumn and scarce in spring, and rare winter visitor; occurs in open and closed-canopy woodland.
IDENTIFICATION
Oct. 2022, Michelle and Peter Wong.
11-12 cm. Rather large and elongate with notable contrast between grey of crown and green edges to wing coverts and flight feathers. Has a long supercilium (yellowish in front of and above eye, whitish behind) bordered by dark eye stripe and median crown stripe; central crown stripe is obvious from above the eye to the hind crown. Usually shows short narrow pale wing bar on greater coverts and sometimes a faint bar on median coverts. Underparts rather white apart from pale yellow wash to rear of vent and on undertail coverts. Lower mandible orange.
VOCALISATIONS
This species appears to call so rarely away from the breeding grounds it is unclear what sound might be heard in HK. The first of the following two, a sharply downslurred ‘tyoo’, is given in alarm but also when more relaxed.
Also, a buzzing ‘ziht’.
Song can occasionally be heard in spring from the last week of March to mid-April. It often contains a distinctive harsh, buzzing upslurred note.
DISTRIBUTION & HABITAT PREFERENCE
The favoured sites of this species are forest areas such as Tai Po Kau and Shing Mun, but it also occurs in widespread areas of trees and mature shrubland, including urban parks and on Po Toi.
OCCURRENCE
Passage migrant, uncommon in autumn and scarce in spring, and rare winter visitor. Extreme dates are 5 August 2018 and 8 May 2008.
Rare in the first half of August, numbers increase from the middle of the month to peak from the second week of September to the first week of October (Figure 1). Subsequently numbers decline to the end of October, after which there is a low incidence of records until the end of the year. The cold months of January and February bring fewest reports. Spring passage is evident from at least the third week of March, peaking in the first week of April, but is much less marked than that in autumn. The highest count is ten at Shing Mun on 6 September 1992.
Previously this species was not considered to occur regularly in winter, but since 2010, and particularly after 2015, there has been a substantial increase in the number of reports. No doubt this is partly due to increased observer activity, but it would appear likely that the milder winters brought by climate change are also a factor.
Given that it was previously considered a passage migrant and winter visitor with differing emphases on each period (Vaughan and Jones 1913, Dove and Goodhart 1955, Herklots 1967, Chalmers 1986), there was obvious confusion among observers over separation of this species from Hartert’s Leaf Warbler. Consequently, records up to 1984 are not considered reliable.
BEHAVIOUR, FORAGING & DIET
Forages rather deliberately and slowly in the forest canopy. Diet includes caterpillars, spiders and insects.
SYSTEMATICS & RANGE
Monotypic. Breeds in Japan and Ussuriland through northeast to north central China; winters in southeast Asia south to Java (Clement 2020, Liu and Chen 2020). HK records indicate the wintering range may extend further north than this.
CONSERVATION STATUS
IUCN: Least Concern. Population trend stable.
Figure 1.
Chalmers, M.L. (1986). Annotated Checklist of the Birds of Hong Kong. Hong Kong Bird Watching Society, Hong Kong.
Clement, P. (2020). Eastern Crowned Warbler (Phylloscopus coronatus), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.eacwar1.01
Dove, R. S. and H. J. Goodhart (1955). Field observations from the Colony of Hong Kong. Ibis 97: 311-340.
Herklots, G. A. C. (1967). Hong Kong Birds (2nd ed.). South China Morning Post, Hong Kong.
Liu, Y. and Chen, Y. H. (eds) (2020). The CNG Field Guide to the Birds of China (in Chinese). Hunan Science and Technology Publication House, Changsha.
Vaughan, R. E. and K. H. Jones (1913). The birds of Hong Kong, Macao and the West River or Si Kiang in South-East China, with special reference to their nidification and seasonal movements. Ibis 1913: 17-76, 163-201, 351-384.
