IDENTIFICATION

VOCALISATIONS

A loud and fast trill that varies in intensity and somewhat in pitch according to mood is uttered by both sexes during the breeding season; accompanied by single very short notes that rise and fall in pitch. Also, a nasal ‘ner-ne’ and a high-pitched ‘pwit’ when anxious or alarmed.

DISTRIBUTION & HABITAT PREFERENCE

The stronghold of Little Grebe is the Deep Bay area, but it also occurs in small numbers at sites in the west, southwest and northeast New Territories, as well as on Lantau. In the breeding atlas of 2016-19, apart from the Deep Bay area it was also recorded in ash lagoons at Nim Wan, two sites in the northeast New Territories and Mui Wo, Lantau. Its breeding season range appears to have shrunk since the 1993-96 survey when it was recorded in 2.8% of 1km squares, compared to 2.4% in the most recent survey. Declines occurred in the northeast New Territories and the margins of the Deep Bay area.

In contrast, it was recorded in a higher proportion of squares in the 2016-19 winter atlas survey (3.0%) compared to the 2001-05 survey (2.4%). Away from the Deep Bay area it was more widespread in the southwest New Territories, Mui Wo on Lantau and Sha Tin in the most recent surveys.

The preferred habitats are fish ponds and gei wai that have emergent or submergent vegetation, especially if there are low numbers of fish. While it is not confined to these fresh or slightly brackish water habitats, it is only rarely seen in sea water, where it is generally confined to sheltered inshore waters such as inner Deep Bay and Shuen Wan. Records at more exposed coasts include one in the harbour at Po Toi on 22 November 2007, one at Nim Wan on 19 March 2014 and one at Fan Lau, Lantau on 28 October 2018.

From 1958 to the late 1960s most records were from Tai Lam Chung Reservoir, where counts of up to 70 were made. Since then, however, the majority of records have been in the Deep Bay area, the primary breeding area, where fish ponds predominate. Only small numbers are recorded on reservoirs now, with the highest recent count being six on Ho Pui Reservoir, the site of most such records.

OCCURRENCE

Little Grebe is present all year, though it is unknown to what extent migration affects this pattern of occurrence or the numbers occurring. Figure 1 illustrates the mean count per month during the systematic waterbird counts from 1979 to 2021, and it can be seen that numbers are highest in early winter and early spring, and lowest in the summer months. This could be explained in terms of the breeding cycle, with birds more visible in early spring due to the demands of courtship and territory protection, less visible in the summer due to females being at the nest and more secretive behaviour at this time, and more visible again in early winter due to the population having been supplemented by birds of the year and their coming together in non-breeding season flocks.

It is possible that migrants do occur to influence this pattern, with some passage in early spring and early winter, as although Little Grebe is regarded as an abundant resident by Birding Beijing (2021), it is presumed the populations further north are migratory, as indicated by Liu and Chen (2020). Records off Po Toi and Fan Lau (above) also support this.

The highest counts of Little Grebe have occurred in the Deep Bay area during winter waterbird counts surveys. The highest count until winter 2014/15 was 352 on 12 January 1986 (of which 309 were on the Shenzhen side of the bay); however, since winter 2015/16 every count has been higher, the highest being 515 on 15 December 2019 (Figure 2). Based on winter waterbird counts in Deep Bay Sung et al. (2021) concluded that the wintering population increased from 1998 to 2017.

Little Grebe is now more numerous than it was for much of the 20^th Century. Vaughan and Jones (1913) noted it was resident but subject to considerable seasonal variation, while Herklots (1967) stated it was not certain that it bred in the New Territories and should be regarded as a winter visitor.

BREEDING

The breeding season can be long, and appears to be affected by rainfall, temperature and site-specific factors. Thus, sheltered water bodies free from disturbance may see breeding activity as early as late January, while heavy rain in the summer that floods out nests may stimulate replacement nests and broods that are visible into November. The earliest date on which juveniles have been noted is 28 January and the latest is 14 November.

BEHAVIOUR, FORAGING & DIET

As Little Grebe thrives in ponds without larger fish, it is presumed insects and their larvae (also the prey of larger fish) form a large part of the diet; small fish are also consumed. It feeds mainly by diving for periods of up to 30 seconds but can also be seen pecking at emergent vegetation.

A characteristic species of the Deep Bay area, Little Grebe is commonly seen swimming and diving on fish ponds and gei wai. While fairly tolerant of disturbance, it cannot generally be closely approached and will skitter across the water to refuge. During the breeding season favoured ponds are the scene of frequent competitive vocalising. In the non-breeding season small groups of up to 20 can form on individual ponds and may remain for a number of weeks.

RANGE & SYSTEMATICS

Widely distributed from Europe and northwest Africa to the Urals, the Caucasus, Iraq, southwest Iran and south Asia through southeast Asia through to northeast China, the Kurils and Japan south through Taiwan to the Philippines and parts of Indonesia; also, in Africa south of the Sahara and Madagascar (Llimona et al. 2020).

In China Little Grebe is a summer visitor to the northeast and northwest and is present all year in lowland areas in much of the rest of the country (Liu and Chen 2020).

T. r. poggei occurs from northeast to southeast Asia, including Hong Kong, Japan and Taiwan. Six other subspecies are also recognised.

CONSERVATION STATUS

IUCN: Least Concern. Population trend decreasing.