IDENTIFICATION

VOCALISATIONS

The typical call is more rolling and rattling than that of Scaly-breasted Munia.

Contact calls include a short nasal ‘bwip’.

DISTRIBUTION & HABITAT PREFERENCE

A widespread but rather localised and sparsely distributed resident. The distribution recorded in the 2016-19 breeding bird survey suggests that White-rumped Munia is commonest on the Kam Tin plain and around Sheung Shui. It is found in most districts of HK but is largely absent from the Deep Bay area and there appear to be very few in the northwest and east and southeast New Territories. It is widespread but localised on HK Island and Lantau, regular but scarce on Cheung Chau, Lamma and Po Toi and apparently absent from other islands. It appears to have declined (at least in range) in recent years: it was recorded from 11.2% of squares during the 1993-96 breeding atlas and 10.2% of squares in the 2001-05 winter atlas survey, but only 6.3% and 5.1% of squares in the 2016-19 breeding and winter surveys, respectively. Geographically, the decline is most marked in the west and northwest New Territories and, especially, on the north side of HK Island where it was formerly widespread.

White-rumped Munia is a bird of transitional habitats, such as forest edge, shrubland, edges of fung shui woods and farmland (where it particularly favours rice fields) as well as city parks and gardens. It is largely a bird of the lowlands and is absent from upland grassland, larger forest blocks and upland shrubland, and largely absent from wetland areas except for anthropogenic freshwater wetland mosaic habitats such as those in Long Valley and Lam Tsuen Valley. At such sites it may be found in mixed flocks with Scaly-breasted Munia but is generally less sociable than that species and is more often seen in pairs or small parties of up to about ten or 20 individuals. Large flocks and aggregations do occur, however, usually in association with an abundance of food. Subsequent to the previous record count of 200 at Cheung Sha Wan poultry market on 31 December 1997 (Carey et al. 2001), higher numbers have been recorded regularly in the rice fields at Long Valley, usually in July, with the highest count on record being 533 birds there on 18 July 2016. Elsewhere, a count of 250 at Lai Chi Wo on 16 July 2014 was unusual, whilst a total of 113 in Lam Tsuen on 1 August 2020 was also associated with rice fields.

OCCURRENCE

The first explicit reference to White-rumped Munia occurring in HK came from Vaughan and Jones (1913), who described it as non-breeding winter visitor or spring migrant (in contrast to its status in other parts of the region including Guangzhou and Macau where they considered it to be a common breeding species). Herklots (1935) was more equivocal describing it as possibly resident but most often seen in March and April suggesting that it was (primarily) a non-breeding visitor at that time. Herklots (1953), which primarily refers to field observations in the 1930s, considered that ‘one day’ nests would be found in the New Territories.

However, it appears to have become very rare in the 1950s: Dove and Goodhart (1955), who were primarily active in the New Territories (notably, in this context, Long Valley and Lam Tsuen Valley), did not observe it and were not aware of its being seen by others post-war. Indeed, Walker (1958) described an observation of a single immature bird at Bowen Road, HK Island on 7 September (the year is not stated but his observations spanned the period from 1955 to 1957) as the first post-war observation. However, in view of the location, and Walker’s observation that it ‘allowed close approach’ it seems possible that it was of captive origin.

There were further records from 1959, with parties of up to 12 noted by 1963, and it was seen annually from 1966 (Carey et al. 2001). Initially most reports came from the Lam Tsuen Valley and HK Island, but there was a rapid increase in numbers and range in the 1970s to the point where it was considered to be well-established in several places on HK Island and the New Territories by 1975, with numbers, if not range, continuing to increase in the 1980s and 1990s (Carey et al. 2001). The reasons for this rapid increase and spread are unknown, though Leven and Corlett (2004) suggested that the pattern indicated that both natural colonisation and large-scale Buddhist ‘mercy’ releases were likely to have taken place.

Whilst it is undoubtedly somewhat nomadic, the extent to which White-rumped Munia is a true migrant in HK is unclear. As is discussed above, Vaughan and Jones (1913) considered that it was a winter visitor and spring passage migrant; meanwhile, Herklots (1953) stated that records in HK were confined to the winter and spring months but expected that nests would be found in HK, suggesting that he was not convinced that it was a migrant. However, systematic observations from Po Toi from 2006-12 demonstrated that it is a primarily a summer visitor there, with most observations falling between late April and early November (G. Welch in litt.).

BREEDING

White-rumped Munia appears to have a particularly long breeding season in HK with an occupied nest noted as early as 26 February 2004 and nest building as late as 10 December 2009. It is presumably multiple-brooded. However, as is noted below, White-rumped Munia builds winter roost nests and some unseasonal observations might relate to these rather than nesting attempts.

Nests are solitary and untidy balls of grass (many observations of nest-building relate to birds seen flying with long trailing strips of grass in their bills) placed in a tree, bush or in a tangle of climbers. They are often placed quite low, typically between one and three metres above the ground (Carey et al. 2001), including near the top of an Araucaria heterophylla tree. The only observation on clutch size from HK concerns three juveniles being fed in September.

BEHAVIOUR, FORAGING & DIET

White-rumped Munia is usually observed as small parties in grass clumps or rice fields where it is not shy and can be seen feeding on seed heads still attached to the plant (and often not yet ripe) or on scattered seeds on the ground. In accordance with its being the only HK munia species that favours wooded habitats, parties can also often be found loafing in bushes, where clumps covered with climbers are often favoured. If flushed it has a characteristic fast ‘bullet-like’ flight, often flying for some distance and disappearing into (rather than landing on) clumps of bushes or up into trees.

Like Scaly-breasted Munia, White-rumped Munia constructs and uses roost-nests in winter, but it is not clear how frequent a practice this is. Vaughan and Jones (1913) observed that White-rumped Munias in Macau had been observed to build nests for roosting in winter, whilst in HK two birds were seen entering a seemingly newly-constructed nest during cold weather at Shek Kong on 23 December 2023.

White-rumped Munia is a granivore and there are numerous observations of it feeding in rice fields. It also feeds on seeding grasses, with a record of it feeding on the seeds of the native Palm-grass Setaria palmifolia is the only observation ascribed to a specific grass species.

RANGE & SYSTEMATICS

Found from Nepal and India in the west, and throughout Southeast Asia south to Sumatra (Payne 2020). Widespread in south and east China north to Sichuan, Shaanxi, Hubei and Jiangsu and in Taiwan (Liu and Chen 2021).

There are six races, two of which occur in China, L. s. subsquamicollis occurs in Yunnan and Hainan whilst L. s. swinhoei is found in the rest of its Chinese range, including HK.

CONSERVATION STATUS

IUCN: Least Concern. Population trend stable.