IDENTIFICATION

VOCALISATIONS

The song is a double-note ‘whoo-whoo’ repeated in a short series.

DISTRIBUTION & HABITAT PREFERENCE

Spring records are predominantly from southern coastal areas, especially on or near Po Toi (65% of the total since 2001), where birds have been observed roosting in tall trees in fung shui woods or in flight over open sea. Elsewhere in spring there are multiple reports from woodland on southern HK Island, Lamma and Lantau and from parks and gardens on both sides of Victoria Harbour. In autumn, in addition to sightings at coastal sites and in urban parkland, there are also occasional inland records in forest or mature shrubland up to 300m asl at Sha Lo Tung, Cloudy Hill, Wo Hop Shek and Tai Po Kau.

OCCURRENCE

Records fall within two periods: 24 March to 26 May and 3 October to 30 November (Figure 1), with the majority (83%) in spring, especially in April and the first week of May. Highest counts are five over the sea near Po Toi on 5 May 2007 and three on Po Toi on 20 April 2013; spring records are otherwise of single birds, occasionally two. All autumn records are of single birds. Most individuals, especially in spring, are thought to remain at a site for only one or two days before moving on, but occasional longer-stayers have been reported in both passage periods, including one at Tai Koo Shing from 24 April to 12 May 1996 and one at Lai Chi Kok Park from 13 to 25 November 2008. The annual total number of individuals since 1999 has varied between zero (2002, 2003, 2019) and 12 (2012, 2013).

The pattern of occurrence of records prior to 1999 was similar to that of recent years (Carey et al. 2001). Following two birds at Stanley Cemetery on 6 April 1968 (Hibi 1969), the first substantiated HK record, the period brought ten further records, all of single birds between 24 March and 12 May apart from one at Cloudy Hill on 18 October 1997. No details of place or date are known for a specimen mentioned by G. A. C. Herklots in an editorial footnote to Williams (1933)

BEHAVIOUR, FORAGING & DIET

This species can be confiding, and birds have been observed roosting in the daytime in large trees in gardens and urban parks, where they can attract mobbing passerines, and perching in early evening near street lamps to fly out after winged termites in spring. Also in spring, birds are occasionally seen flying in circles over open sea during the day-time.

RANGE & SYSTEMATICS

Three subspecies are recognised: N. j. florensis breeds in the Russian Far East, north and northeast China and North Korea, N. j. japonica breeds in South Korea and Japan, and N. j. totogo breeds on the Ryukyu Islands and Taiwan. Both florensis and japonica are long-distance migrants wintering south to the Sundas, Philippines and Wallacea, whilst totogo is mostly resident (Konig & Weick 2008). In China, Liu and Chen (2020) regard all mainland birds as japonica and state it is also a winter visitor to the southern half of the country, though the pattern of records in HK does not indicate this.

Historically, spring passage was known to be strong along the coast of southeast China, with La Touche and Rickett (1912) reporting a total of 112 birds observed in a single spring (16 April-13 June 1911) on Shaweishan Island off Shanghai.

CONSERVATION STATUS

IUCN: Least Concern. Population trend stable.