IDENTIFICATION

VOCALISATIONS

The song is rich, loud, varied and generally unmistakeable. Some birds employ much mimicry including, notably, Large Hawk Cuckoo, late summer and autumn reports of which often refer to this species. Also commonly heard are Crested Serpent Eagle, Crested Goshawk and the song of Asian Koel (uttered slightly lower in pitch than the original). Other mimicry includes car alarms, Black-naped Oriole and even Chinese Bamboo Partridge Bambusicola thoracicus.

Perhaps the most distinctive frequently-heard calls are a fairly low-pitched and throaty ‘werk’, ‘wek’ or ‘wuh’, a similar but higher-pitched and sharply downslurred ‘kerk’ or a sharply inflected ‘kuwerk’. While usually uttered singly or in a short series, these notes may be uttered in long series, especially if other birds are present. Contact calls when foraging include a short ‘wik’, a rather flat ‘kerk’ and an extended nasal muffled chatter interspersed with higher-pitched calls. A louder and anxious drawn-out chatter is uttered when alarmed. It is unknown if vocalisations of hybrids differ.

Recordings of this species are not freely available on Xeno-canto.

DISTRIBUTION & HABITAT PREFERENCE

Black-throated Laughingthrush is primarily found in forest and closed-canopy shrubland, preferring forest with a dense shrub layer. Thus it tends to be absent from eucalypt and acacia plantations unless a shrub layer is present. It occurs at all elevations, from sea level to the top of Tai Mo Shan, and whilst it is usually commonest at middle elevations in the hills, this is probably a consequence of habitat presence rather than an altitudinal preference. There is some evidence that, as it has become commoner, Black-throated Laughingthrush is spreading into more marginal habitats including well-wooded city parks on HK Island and small woodland patches around villages in the northwest and north New Territories.

As forest matures and succession from open-canopy to closed-canopy shrubland takes place there has been an interesting change in the distributions of Black-throated Laughingthrush and Chinese Hwamei. The latter species was much the more widespread at the time of the first breeding atlas, occurring in 43.3% of squares compared with only 5.2% for Black-throated Laughingthrush. However, by the time of the second breeding atlas Black-throated Laughingthrush was marginally the more widespread of the two species, occurring in 28.1% of squares as against 27.1%. However, it is unclear if Black-throated Laughingthrush actually excludes Chinese Hwamei, or if Chinese Hwamei abandons sites as succession continues.

OCCURRENCE

As is stated by Carey et al. (2001), the early history of Black-throated Laughingthrush in HK is somewhat obscure, but it was reported from HK Island by Vaughan and Jones (1913), who were clearly familiar with its song. It was not mentioned by Herklots (1936) in his review of the laughingthrushes of HK, and in Herklots (1967) he noted that despite his ‘having been studying the birds of the Colony more or less intensively for nearly twenty years’ it was not until 15 April 1948 that he first saw and heard one in his garden in Pok Fu Lam. As stated by Carey et al. (2001), by the late 1950s it was considered to be widespread on HK Island, though observers at the time suggested that the apparent increase might have been, at least in part, due to observers becoming more familiar with its song. In retrospect, however, it is not implausible to suggest that the population noted by Vaughan and Jones subsequently disappeared and that the Black-throated Laughingthrush population noted from 1948 was derived from ex-captive birds that were released or escaped in the interim. Black-throated Laughingthrush was first reported from the New Territories in 1962 when one was heard singing at Tung Chung, Lantau, and first reported from the mainland New Territories on 11 January 1964 when two were heard singing at Tai Lam Chung. Subsequently, however, there were only a handful of widely scattered reports from the New Territories until 1990, all of single birds apart from a series of reports from Cheung Chau during 1987 to 1989.

In the 1990s both distribution and numbers in the New Territories increased and by the time of the first breeding bird survey (1993-1996), when it was reported from 5.2% of squares, there were concentrations around Shing Mun and Ma On Shan, together with scattered reports from elsewhere, including on Lantau; meanwhile it was one of the most widely distributed species on HK Island.

This century the increase and spread continued, and it was found in 5.6% of squares in the first winter survey (2001-2005) despite its being less conspicuous when not singing. Since then it has spread even further, such that by the time of the second breeding and winter surveys it was found in 28.1% and 17.0% of squares respectively and was widespread in the central, northeast, east and southeast New Territories as well as in its original stronghold on HK Island. It remained absent from the dense urban neighbourhoods on the north side of Victoria Harbour between Tsuen Wan and Tseung Kwan O, whilst there were few in the northwest New Territories where there is limited suitable habitat, and, perhaps more surprisingly, in the north New Territories. Other than on Lantau, where it is widespread, albeit sparsely distributed, it remains absent from the offshore islands, including Cheung Chau (where a population appeared to be established in the late 1980s, but it has not been recorded since 2003).  

Small numbers of dark-cheeked birds, wholly or largely lacking the bold white cheek patch of nominate Black-throated Laughingthrush, have been noted annually in HK since 1 March 2006, when one was seen at Ng Tung Chai. Such birds were initially ascribed by observers to the dark-cheeked ‘lugens’ morph of P. c. chinensis, which is considered by Robson (2000) to be probably restricted to Laos and Vietnam. However, since 2014, when one was seen at Tai O, Lantau on 14 October, there have also been annual reports of birds of the Hainan race, P. c. monachus, as well as reports of apparent hybrids between these two forms, between both these forms and nominate chinensis, as well as records not ascribed to form but submitted as not typical [white-cheeked] chinensis.   The Records Committee of HKBWS concluded that all such records up to 2017 for which some form of substantiation was available for inspection referred to monachus.

We reviewed available photographs of ‘non-typical’ individuals in HK since 2017, Black-throated Laughingthrushes from HK, Laos and Vietnam and a sample from southwest China (eBird 2024) and concluded as follows:

• All non-typical Black-throated Laughingthrushes from HK for which substantiation is available for review are either P. c. monachus or hybrids between P. c. monachus and P. c. chinensis.

• In addition, whilst not going so far as to state that the ‘lugens’ morph has never occurred in HK or China, we have found no photographic evidence of this morph having been recorded outside the range in Laos and Vietnam range described by Robson (2000).

The range of P. c. monachus (and hybrids) in HK has not been fully determined; however, it seems that reports are concentrated in the central New Territories from Ng Tung Chai south to the Kowloon Hills, and especially at Tai Po Kau. However, there are also reports of monachus and/or hybrids from elsewhere including the northwest New Territories, Sai Kung, HK Island and Lantau.

In view of the frequency of apparent hybrid pairs, mixed parties and birds showing hybrid features it appears that there are few, if any, barriers restricting interbreeding between the taxa. Thus, whilst numbers of monachus and hybrids are apparently relatively small at present, there does seem to be a real possibility that hybridisation could be, and perhaps already is, a threat to the integrity of the HK population of this species.

In order to monitor the significance of this hybridisation issue, as well as to clarify the distribution of monachus and hybrid birds, observers are encouraged to submit details of all non-typical birds seen, and to state which taxon or hybrid taxa in all records.

Whilst its spread has clearly demonstrated its dispersal capabilities, there is no evidence that Black-throated Laughingthrush makes any regular, or even occasional, movements, as is evinced by its failure to colonise offshore islands (it has never been recorded on Lamma, for example). Whilst this evidence does support the decision to place Black-throated Laughingthrush on Category IIA of the HK list rather than Category I, it also suggests that the recent occurrence of monachus not just in the central New Territories, but also on HK Island and Lamma is most likely also to be a consequence of releases of birds at these locations.

BREEDING

Singing occurs throughout the year, albeit it appears to be more intense from about March to June. One was observed carrying nesting material on 1 April, a bird was observed carrying food to a nest 3m high in bamboos on on 11 April and nest-building (at about 2m above the ground) was noted on 12 May. Recently fledged young have been noted between 2 June and 14 September suggesting that more than one brood may be raised. However the nest and eggs have not been described in HK. A Chestnut-winged Cuckoo observed in a flock of Black-throated Laughingthrushes at Tai Po Kau on 2 July 2010 suggests it may be a host species for the cuckoo on occasion (Greater Necklaced Laughingthrush appears to be its primary host species).

BEHAVIOUR, FORAGING & DIET

In some respects Black-throated Laughingthrush displays behavioural characteristics that are intermediate between Chinese Hwamei (usually found as pairs or at most family parties and keeps low to the ground in dense cover) and Greater Necklaced Laughingthrush (which moves around in large often quite fast-moving flocks, often up to 20 or so individuals, which spend much of their time in the middle levels of the tree layer). Black-throated Laughingthrush may be found as singletons or pairs, especially where it is less common, but more typically in the non-breeding season is found in groups of about four to six individuals, which move slowly through the shrub layer or on the ground (where birds will rummage through the leaf litter). On occasion parties will join mixed species flocks, including with Greater Necklaced Laughingthrush. Presumably when they do this, they opportunistically catch invertebrates or consume fruit, but there is an absence of systematic observations.

Singing birds most often do so from within the shrub layer, both in shrubland and forest, and hence often go unseen, but sometimes one will sing from a perch in the open in shrubland, especially in the early morning, at which time song is usually most intense. Typically Black-throated Laughingthrush is rather shy and retiring, but birds in city parks may become habituated to people and confiding (as, for example, in a few locations on HK Island where individuals have learnt to take advantage of food scraps provided by people).

Black-throated Laughingthrush spends most of its time, and presumably finds most of its food, within, or on the ground under, the shrub layer in forest and closed canopy shrubland. Diet of this insectivore-frugivore is little studied in HK: Leven (2000) observed fruit remains in one and invertebrate (Isoptera, Formicidae and Coleoptera) remains in all four faecal samples which he examined, whilst Corlett (1998) noted remains of fruit of three plant taxa in faecal samples. There is also an observation of one eating a stick insect (Phasmatodea).

RANGE & SYSTEMATICS

The native range extends from Myanmar in the west, south to central Thailand and through to eastern China. In China it is widespread in Yunnan, Guangxi and western Guangdong (eBird 2022, J. Martinez in litt.). Though Liu and Chen (2021) showed its range covering all of Guangdong and Fujian Provinces, in central Guangdong most records come from urban locations around the Pearl River Delta, and likewise in Fujian Province it appears to primarily occur around Xiamen (eBird 2022). This suggests that in at least some of its range in southeast China the populations may derive from ex-captive birds. Cheng (1987) considered that it occurred no further east than the west side of the Pearl River. Outside its (putative) native range feral populations are established in Taiwan and Singapore.

IOC recognises five subspecies, three of which occur in China, including P. c. lochmius in southwest Yunnan, the nominate form in the remainder of south China (including HK) and P. c. monachus in Hainan. The latter is distinctive and is sometimes split (including by Liu and Chen 2021) as Hainan Laughingthrush P. monachus. The ‘lugens’ morph is understood to probably occur only in the Indochinese population of P. c. chinensis (Robson 2000).

CONSERVATION STATUS

IUCN: Least Concern. Population trend decreasing.