IDENTIFICATION

VOCALISATIONS

The typical call heard when taking flight, including when flushed, or when landing is a harsh ‘kyaaaar’, usually repeated several times.

DISTRIBUTION & HABITAT PREFERENCE

In most places the default egret and seen in a wide variety of habitats. Little Egrets occur in low-lying wet and coastal areas throughout HK in freshwater marshes, brackish fish ponds, gei wai shrimp ponds, intertidal mudflats, inshore fish culture structures and natural or man-made rocky marine shores. In 1958 they were recorded feeding in rice fields, but since these disappeared, they have adapted well to the increased impact of man on the environment and remain common in such heavily anthropogenic areas as Sha Tin and Victoria Harbour. In the northwestern New Territories, drained down fish ponds and gei wai are a particularly important feeding habitat for Little Egrets, with 900 birds recorded in a single drained fish pond by Young and Chan (1997), and up to 1680 birds in a drained gei wai on 20 October 1994 (Ma 1997).

OCCURRENCE

Little Egrets are present year-round. Figure 1 illustrates the pattern of occurrence in the Deep Bay area as recorded by systematic monthly waterbird counts since 1998 and indicates that numbers are highest from September to February when the mean monthly count averages over 1,000, peaking November to January. This suggests that numbers are supplemented by birds from further north.

Numbers decline to a low in May, suggesting departure from HK, though the presence of birds at breeding colonies is presumably also a factor in the low numbers recorded in waterbird counts in foraging areas. An increase in numbers subsequently occurs that is possibly associated with breeding activities and the presence of locally-reared juveniles. That evidence of passage in spring has been recorded from 26 March to 15 May (highest count 100 on 22 April) and in autumn from 6 September to 6 November (highest count 392 on 2 October) suggests also that birds may arrive from areas further south.

Figure 2 illustrates the peak winter period count in waterbird counts since 1979. From the mid-1980s, when access to the intertidal area of Deep Bay improved greatly, to 2009/10, peak winter counts on the HK side of the bay have generally lain in the range 1,000 to 1,800 birds, with the peak count being 1,966 on 13 January 1990. Numbers since 2010/11, however, have been somewhat lower, in the range 700 to 1,200. In addition, from winter 2000/01 to winter 2008/09 notably high numbers were recorded on the Shenzhen side of Deep Bay, with the peak count for the whole of Deep Bay being 3,212 on 12 December 2004. A similar trend was recorded for the Great Egret.

Dark forms of the Little Egret were recorded in most years from 1968 to 1995. Subsequently, there were records in 1999 and in six years from 2010 to 2020. Most reports concerned single birds, occasionally two.

Previously, Vaughan and Jones (1913) reported that Little Egret was a migrant to southeast China and that it was more common in spring and autumn. Herklots (1953) suspected that in autumn most birds that bred in HK migrated south and that their place was taken by migrants from the north, which appears correct. In contrast, Macfarlane and Macdonald (1960) wrote that the species was a resident with breeding records in HK.

BREEDING

Little Egrets were recorded breeding at the Yuen Long North and Yuen Long South egretries from 1958 until 1960, after which these sites were abandoned. In July 1961 breeding was first recorded at Starling Inlet (Yim Tso Ha) and continued there until the colony was abandoned in 1994 and the birds moved to the adjacent island of A Chau. Other major breeding sites in the past have been situated at Nam Sang Wai (60 pairs on 2 May 1971), Au Tau (1971-1974, with a peak of 50 nests on 26 March 1974), Lok Ma Chau (1974-1991, with a high of 150 pairs on 24 June 1974), Tsim Bei Tsui (1984-1990, with a peak of 226 nests in 1989), Mai Po Village (1958 to the present, with a peak of 130 nests in 1986), and Shuen Wan (1991-1995, with a minimum of 50 pairs in 1991).

Figure 3 illustrates the number of nests recorded during annual census from 1998 to 2021 in Deep Bay and non-Deep Bay areas. The overall trend is one of increase from something in the region of 200-250 nests to 400-450 since 2015 (when numbers of Chinese Pond Heron nests have also been high). There appears to have been no significant change in the distribution of nests, with the Deep Bay area continuing to support 40% to 60% of discovered nests.

Studies of Little Egrets breeding at the Mai Po Village Egretry showed that birds fly up to 4km to feed and that the main feeding habitats are the areas of commercial fish ponds surrounding the colony (Wong 1991). It has been shown that the decline in the number of Little Egrets breeding at a colony from 1981 to 1993 was correlated with a decline over the same period in the area of fish ponds due to in-filling for development (Young 1998). Other causes of colony decline or abandonment are human disturbance and predation during the sensitive period of the breeding cycle (as at Yuen Long egretries) and death of the trees used for breeding due to smothering by climbers such as the exotic Mikania micrantha (as at Yim Tin Tsai).

BEHAVIOUR, FORAGING & DIET

Little Egret is able to exploit a variety of foraging opportunities, which helps explain its abundance. Normally solitary when foraging, it readily exploits in large, dense flocks the feeding opportunities provided by commercial fish ponds or gei wai in the process of drain-down. It uses a range of foraging behaviours to capture prey, including walking (most commonly), standing, chasing and following fishing boats to capture prey while in flight. It has been recorded capturing fish (including Bostrychus sinensis), mudskippers and dragonflies (including Pantala flavescens).

Nine Little Egrets were tracked using GPS data loggers for 14 months to study spatial ecology, home range, movement and habitat use (Pang et al. 2022). Over 88% of the typical home range comprised a diversity of wetlands, among which commercial fish ponds were most frequented. The largest home range, furthest movements and most frequent visits to commercial fish ponds occurred in the winter.

Pang et al. (2023} studied inter-annual breeding and wintering site fidelity of an adult and a juvenile. Both individuals displayed high site fidelity and had very small winter home ranges, probably associated with high prey availability in aquaculture ponds. Both birds migrated to breeding grounds in Anhui Province, China, approximately 1,159 km northeast of HK.

Roosts and nests communally throughout the year. So and Yuen (2020) surveyed ardeid roost sites across Hong Kong in winter 2019/20 and recorded 3,066 Little Egrets across 23 of the 26 known roost sites, with highest numbers in Deep Bay, around Tolo Harbour and at Ap Lei Chau, Tuen Mun and Tsuen Wan. The highest roost count is 950 at the Lok Ma Chau MTRC mitigation wetland area on 30 September 2020, with other counts of over 900 having also occurred at Tam Kon Chau and Tai Po.

Appears to migrate largely by day as recording of nocturnal migration over Pak Sha O, Sai Kung from 2017 to 2021 did not record this species but did record other ardeids.

RANGE & SYSTEMATICS

Occurs from Europe and sub-Saharan Africa east to Japan and south through India and southeast Asia to Indonesia and Australasia (del Hoyo et al. 2020). In China a summer visitor to areas north of the Chang Jiang and present all year to the south (Liu and Chen 2020); small numbers remain in the winter as far north as Beijing (Birding Beijing 2022).

The nominate subspecies occurs from Europe to Japan and south to Africa, India and the Philippines, including HK, while E. g. nigripes occurs from Indonesia to Australasia.

CONSERVATION STATUS

IUCN: Least Concern. Population trend increasing.