IDENTIFICATION

VOCALISATIONS

The voice is high-pitched and at times rather frantic: ‘kirrit’ or rapidly repeated versions of this in excitement or agitation.

RANGE & SYSTEMATICS

Breeds locally in Europe and north Africa, more continuously from eastern Europe to Kazakhstan and south of the Caspian Sea, and in east Asia from southwest China to Ussuriland and Japan; winters coastally from southeast Asia to Australia, the Indian subcontinent and the Middle East, with scattered year-round populations in Africa (Gochfeld et al. 2020). In China the nominate taxon occurs in Xinjiang while sinensis is a summer visitor to the rest of the country (Liu and Chen 2020). Hong Kong lies in its breeding range.

Three subspecies are recognised, among which S. a. sinensis breeds from the Indian Ocean through east and southeast Asia to Australia and is presumed to occur in HK. The nominate occurs to the west of here, while S. a. guineae occurs in Africa.

DISTRIBUTION & HABITAT PREFERENCE

Most records are from the Deep Bay area where birds are seen at Mai Po NR, fish ponds and intertidal areas. Away from here it is recorded from diverse coastal and inshore locations, in particular southern waters where increased observations since 2006 have brought a number of records of migrating birds, the highest count being 60. Of particular note is the passage of a tropical storm during 1-2 May 1999 that saw 536 counted at Cape D’Aguilar.

OCCURRENCE

Passage migrant, common in spring and scarce in autumn (Figure 1). March records are less than annual and, although the earliest record for Hong Kong is of a single bird at Kai Tak during 4-6 March 1979, since 1999 the earliest is of one on 22 March 2006, while eight is the highest count for that month.

Figure 1 indicates a peak of passage in the first week of May; however, this is largely due to approximately 635 birds being seen during 1-3 May 1999 in association with the passage of a tropical storm (including 400 off Cape D’Aguilar on the 2^nd). In a typical year it seems the peak of passage occurs in the last week of April. This is later than that for the period up to 1998, though in part this is likely due to increased observer activity in sea areas, particularly in the vicinity of Po Toi. The highest count not associated with a tropical storm is of 80 at Mai Po on 6 April 1991. Passage is generally over by early June, and the period from 6 June to 3 September has seen no more than six birds recorded, apart from 30 on 8 June 1980.

Autumn passage is weak, and from 1983 to 1990 there were no records in this season. An autumn record of 50 flying east at Ting Kau on 19 September 1976 during the passage of Typhoon Iris is by far the highest at this time of year. The peak count since 1978 is nine on 20 September 2014, the month when most autumn records occur. The latest autumn date is of one at Mai Po on 9 November 1991.

Figure 2 illustrates the variation in peak spring counts since 1986 when access to the intertidal mudflats was possible due to the construction of the boardwalk hide; to better illustrate typical numbers, however, it excludes the tropical storm related counts of early May 1999.

BEHAVIOUR, FORAGING & DIET

Prolonged hovering on rapidly beating wings with frequent plunge-diving for small fish is a characteristic trait of foraging Little Terns. Quarters back and forth over foraging area, sometimes in groups.

CONSERVATION STATUS

IUCN: Least Concern. Population trend decreasing.