IDENTIFICATION

VOCALISATIONS

The vocabulary is diverse and often mimetic, with Hair-crested and Ashy Drongos frequent models. The contact call is a loud ringing ‘tink’, often repeated several times.

More commonly heard calls include the following.

The song appears to be a quieter medley of these and various other notes that is easily overlooked.

DISTRIBUTION & HABITAT PREFERENCE

Red-billed Blue Magpie requires trees but is not a forest species, favouring woodland edge, large gardens and closed-canopy shrubland, and is often to be found in woody thickets in river valleys and ravines. Wandering birds occasionally occur in atypical habitats such as mangroves or in dense urban areas. This phenomenon is most frequently observed in spring, suggesting dispersal in search of suitable breeding territories.

Widespread and common on the mainland and many larger islands, but not on smaller islands such as Tung Ping Chau and the Soko Islands. Range expansion was detected by the winter atlas surveys of 2001-05 and 2016-19, with occupied 1 km squares increasing from 14.8% to 20.2%. In contrast, the breeding bird surveys of 1993-96 and 2016-19 revealed a slight decrease in distribution, from 17.3% to 16.9% of 1km squares. The urban population was estimated at 3,097 individuals in 2021 as part of an urban bird survey carried out by HKBWS.

The single documented change in range is the colonisation of Cheung Chau Island, which occurred during the early 1990s. Otherwise, the only evidence of changes in status are an increased frequency of reports from Mai Po during the 1990s as planted trees matured and, conversely, a gradual decline in the urban area of HK Island, where birds are much less frequent in Central than during the 1960s and 1970s, and a decline at the urban fringe in Mid-Levels (Viney 1995).

The first record of Red-billed Blue Magpie was documented by Swinhoe (1861), who found it common on HK Island, an observation echoed by subsequent observers. Vaughan and Jones (1913) later noted that it was widespread in the New Territories, but neither as ubiquitous nor as conspicuous as on HK Island.

OCCURRENCE

Red-billed Blue Magpie is mainly sedentary, without any notable geographical or altitudinal movement. Sightings are generally fewer in summer, when birds are paired-up and less likely to form larger parties. Outside the breeding season it typically occurs in groups of up to ten birds, with the highest such count being 29 on the University of HK campus on 4 October 2018. Sightings increase in autumn when young birds are fledged, and post-breeding dispersal is apparent.

BREEDING

Unlike the closely related Taiwan Magpie U. caerulea which is a social breeding species (Severinghaus 1987), Red-billed Blue Magpie appears to be a solitary breeding species in HK. However, Vaughan and Jones (1913) noted young from a previous brood attending construction of a second nest, so there is a possibility of cooperative breeding.

The breeding season extends from April to August. Fledglings begin to appear in May but have been noted as late as August. Birds can become aggressive even to humans during breeding season, if nests are approached too closely.

This species is a host of Asian Koel in HK (Lewthwaite 1995). A brood of three Asian Koels was also observed in a Red-billed Blue Magpie’s nest in Ho Man Tin on 12 April 2018.

BEHAVIOUR, FORAGING & DIET

Outside breeding season, most often occurs in group up to 20 individuals. Omnivorous, it has been noted to prey on insects such as Brown Cicada Graptopsaltria nigrofuscata and feed on the flowers of Hibiscus tiliaceus and the fruit of Alocasia macrorrhizos and Carica papaya.

RANGE & SYSTEMATICS

Resident from the western Himalayas east through Indochina to China south of a line from north Yunnan to Hebei province, including Hainan (Madge 2020). Of the three subspecies occurring in China, U. e. erythroryncha is the only one in HK, which breeds in central, south and southeast China, including Hainan.

CONSERVATION STATUS

IUCN: Least Concern. Population trend stable.