IDENTIFICATION

VOCALISATIONS

The song, which is uttered much of the year, is a loud and rich though simple phrase of 4-7 notes, with the latter two or three modulated. Calls include a fairly low-pitched ‘chuk’ or ‘chik’, while foraging groups may utter a loud chattering.

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

DISTRIBUTION & HABITAT PREFERENCE

The core distribution of Silver-eared Mesia extends from Shing Mun in the west to Ma On Shan in the east, with outlying records in the northeast and southeast New Territories; the largest numbers occur on the Tai Mo Shan massif. It was recorded from 2.5% of squares in the first breeding atlas (1993-96) and 1.9% of squares in the first winter atlas (2001-05), and 3.4% of squares in the breeding season and 2.4% of squares in winter in the atlas surveys of 2016-19; the apparent smaller range in winter in both survey periods probably reflects the ease with which singing birds can be detected in the breeding season.

The main changes between the two survey periods is an expansion of the core range eastwards into the Ma On Shan area (it was not known from east of Sha Tin at the time of the first pair of surveys); and, conversely, the apparent disappearance from the west of HK Island, which Carey et al. (2001) suggested was a stronghold. This may in part be a survey artefact as it continues to be recorded there, especially in the Lung Fu Shan area, though records on eBird (2023) do suggest that it has become less frequent and present in smaller numbers on HK Island this century. However, even leaving the status on HK Island aside, this species has not shown the recent dramatic increase and spread shown by some other small babblers with populations believed to be derived from ex-captive birds, notably Rufous-capped Babbler and Blue-winged Minla.  

The reasons for its relatively slow increase are unclear. Unlike the other forest babblers with recently established populations, which have no very close relatives in HK, Silver-eared Mesia co-exists with, and indeed is often found in the same flocks as, the rather similar and congeneric Red-billed Leiothrix. Leven and Corlett (2004) speculated that the two species might be in direct competition. However, if this is the case, such competition appears to favour this species rather than the Leiothrix; whilst both species were recorded from a very similar number of squares in the first breeding atlas and winter surveys, the Leiothrix was found to have declined in range in the second pair of surveys (from 2.4% in summer and 1.9% in winter to 1.4% in summer and 1.1% in winter).

There may also be some altitudinal segregation: in the Indian Himalayas where both species are native and are often found together in flocks, Red-billed Leiothrix breeds at higher altitudes, albeit with overlap (Salim Ali and Ripley 1996). Though they do not state that this is the case, it may be that mixed flocks are primarily a feature of winter when both species make altitudinal movements there. Indeed, whilst systematic data is lacking, there is some evidence of altitudinal segregation in HK: whilst the core range of both species is the Tai Mo Shan massif, Silver-eared Mesia is rarely reported from the higher slopes of Tai Ma Shan itself where Red-billed Leiothrix is relatively common (eBird 2023).   

Silver-eared Mesia primarily occurs in secondary broadleaf forest, especially where there is a well-developed understorey, and it can be found in closed-canopy shrubland, perhaps largely outside the breeding season. Records from more anthropogenic habitats such as city parks are presumed to be of ex-captive birds.

OCCURRENCE

As is discussed in detail by Carey et al. (2001), Silver-eared Mesia was first recorded in HK when one was seen at Hatton Road, HK Island in December 1970,  but this turned out to be an isolated record and it was not seen again until two were noted in Tai Po Kau on 7 December 1987. Following sporadic records in the next two years, in the winter of 1990-91 it was seen regularly in Tai Po Kau where two flocks of at least 20 birds were noted on 8 December 1990. Birds were also seen elsewhere, notably at Shing Mun where up to 30 were noted in late 1992 and there were scattered reports from elsewhere, notably HK Island, as is discussed above. As a consequence Silver-eared Mesia was admitted to the HK List, but, as a non-migratory species occurring naturally no closer to HK than Guangxi, natural colonisation was considered implausible and it was was placed in Category IIB as an established exotic species (Carey et al. 2001).

Flocks of 20 – 30 birds are now regularly seen, especially in the core range; the highest count is of 60 at the Shek Kong Catchwater on 28 September 2018, whilst the largest single flock appears to be 50 feeding in Ficus trees at Tai Po Kau Park on 26 December 20016.

There is no evidence that Silver-eared Mesia makes anything other than local dispersive movements, as its rather slow spread in HK suggests. The HK Island records discussed above are assumed to constitute a separate ex-captive population to that in the New  Territories and there are no records from the other islands.

BREEDING

Silver-eared Mesia has been reported showing ‘nesting behaviour’ on 18 April and carrying nesting material on 31 May, and recently fledged juveniles have been seen between 29 April and 20 September, suggesting that it is multi-brooded. However, the nest and eggs in HK have not been described.

BEHAVIOUR, FORAGING and DIET

Except when breeding, Silver-eared Mesia is usually found in flocks, either on its own, with Red-billed Leiothrixes, or with other small babblers and warblers. Flocks are typically of about five to 20 individuals. When in flocks it forages from deep in the understorey to the lower canopy (though not usually at the top of the canopy). Conversely, singing birds are usually solitary, and birds often sing from deep in the understorey, where they can be hard to see well.

Like other small babblers, Silver-eared Mesia is an insectivore-frugivore, and was considered to be highly frugivorous by Corlett (1998) who found fruit remains in 97% and invertebrate remains in 87% of faecal samples examined. It has been observed feeding on the fruit of Schefflera octaphylla, a common native shrub and small tree that fruits in midwinter (December to February) as well as Ficus sp. There is also a report of it feeding in the flowers of the common exotic Paperbark Tree Melaleauca cajaputi, though it is unclear from the report whether it was eating the flowers and/or nectar or invertebrates that had been attracted to the flowers.

RANGE & SYSTEMATICS

Silver-eared Mesia occurs from northwest India, eastwards through Nepal and throughout most of continental southeast Asia south to the Malay peninsula, and on Sumatra (Collar et al. 2020). In China the native range extends from south Tibet eastwards to central Guangxi (eBird 2023). Liu and Chen (2021) indicated that it extends into south Guangdong, but the pattern of eBird records, which are centred around Guangzhou, Shenzhen and Macau, strongly suggests these relate to ex-captive birds or their descendents, as is the case in HK.

There are five races, three of which occur naturally in China: L. a.  argentauris in western Yunnan, L. a. vernayi in eastern Tibet and northern Yunnan, and L. a. ricketti (with which the previously recognised race rubrogularis recognised by Cheng (1987) has been synonomysed) in southern and eastern Yunnan and western Guangxi. Birds in HK have not been ascribed to race but appear to match the description of ricketti in Robson (2000).

CONSERVATION STATUS

IUCN: Least Concern. Population trend decreasing.