IDENTIFICATION

VOCALISATIONS

Not noted to vocalise in Hong Kong, but elsewhere a modulated and whistled ‘tee-chooeee’ is reported.

DISTRIBUTION & HABITAT PREFERENCE

Reports are from the open sea, islands, hilltops and a wide range of wooded and semi-wooded habitats, occasionally also from marshes and city park in widespread parts of the New Territories. Good vantage points for observing visible migration tend to produce the highest numbers, in particular Po Toi, which is the southernmost point of Hong Kong.

OCCURRENCE

First recorded at Mai Po on 31 March 1977, Grey-faced Buzzard is common in spring but scarce in autumn, with approximately 90% of reports in the former season (Figure 1). Passage is concentrated into the period from the last week of March to the last week of April, and particularly the first three weeks of that period, peaking in the first week of the month. Extreme spring dates are 10 March 2015 and 11 May 2019.

In spring it usually occurs in groups of up to 20 birds but occasionally in larger numbers under favourable conditions, usually easterly winds. The strongest passage was recorded in 1993 when 42 were at Cheung Chau and 56 were at Aberdeen CP on 21 March, and 57 were at Tsim Bei Tsui, 147 were at Mai Po and 24 were at Aberdeen CP the following day. Other high counts include at least 106 at Cheung Chau on 24 March 1996, 100 at Mai Po village on 13 April 2001 and 98 on or over Po Toi on 2 April 2008. In spring, most birds appear to arrive from the south or east over the sea and head north or northeast.

Numbers and frequency of occurrence are much lower in autumn, with passage mainly from the last week of September to the last week of October. Most reports refer to single birds or flocks of up to six, with the highest being an exceptional 60 over south Lantau on 28 September 2017, which is also the earliest autumn date. The latest autumn date is 12 November 2017, and there are four winter records from 6 December to 11 February, all since 2007.

Grey-faced Buzzard was likely overlooked before 1977. The only records traced prior to 1958 concern a specimen in the British Museum Natural History (Tring) which is labelled as collected in Kowloon on 5 April 1901. In addition, an editorial footnote to Williams (1933) stated one was collected in ‘winter of 1924-25’; however, the latter is a rather misleading since the dates of Williams’s visit to Hong Kong (13 October to 17 April) also covered parts of both autumn and spring.

Although Kershaw (1904) and Vaughan and Jones (1913) considered this species a not uncommon winter visitor to parts of Guangdong, including the coast, the latter authors described its food as being ‘usually fish’ and referred to its habit of perching on paths and stone walls, suggesting a typographic error.

BEHAVIOUR, FORAGING & DIET

One of only two raptor species that regularly passes through HK in sizeable flocks, and during suitable weather conditions it can be seen in large numbers on spring migration. Considerable year-on-year variation in numbers occurs as passage is heavily influenced by weather patterns, arrivals typically occurring two to four days after surges of the northeast monsoon, with the Philippines being the likely source of birds (Lam and Williams 1994). As with the other weather-influenced raptor migrant Chinese Goshawk, Grey-faced Buzzards generally pass through quickly.

RANGE & SYSTEMATICS

Monotypic. Breeds in northeast China, Ussuriland, the Korean peninsula and Japan south of Hokkaido; winters Indochina and southeast Asia to the Greater Sundas (Orta and Marks 2020). In China a summer visitor to the northeast and migrant through much of the country (Liu and Chen 2020). Wintering in southeast China appears to be very rare based on the pattern of occurrence in HK and Hainan (Lewthwaite et al. 2021), despite the literature cited above indicating that the species winters in southern coastal provinces.

CONSERVATION STATUS

IUCN: Least Concern. Population trend decreasing.