Black Baza Aviceda leuphotes 黑冠鵑隼
Category I. Uncommon passage migrant in autumn, scarce in spring and rare in summer. Has declined by 40% or more this century. Occurs in open woodland in summer and over a variety of habitats on migration.
IDENTIFICATION
Jul. 2022, Michelle and Peter Wong.
28-35 cm. Compact, small to medium broad-winged raptor with tall crest. Distinctive pied plumage pattern comprising black head, throat, crest, upperparts, tail, broad band across chest and vent; variable rufous or blackish barring on belly.
Jun. 2021, Michelle and Peter Wong.
Underside of primaries pale with dark tips, secondaries dark grey, underwing coverts blackish apart from greyish primary coverts. Upperparts have variable broad white tips to tertials and scapulars and pale secondaries.
VOCALISATIONS
Birds are often vocal when displaying and have also been heard calling during autumn migration.
DISTRIBUTION & HABITAT PREFERENCE
Migrants utilise woodland of all kinds and have been recorded from widespread parts of the New Territories, though it appears rather scarce on Lantau. Birds in summer show a preference for pine-dominated hillsides and are more locally-distributed, occurring mainly in the central and eastern New Territories, and occasionally also in the northern New Territories.
OCCURRENCE
Migrant Black Bazas are reported mainly from mid-April to mid-May, with a peak in the second half of May, and in October, peaking in the first half of the month (Figure 1). The earliest on record occurred on the exceptional date of 16 February 2002 in Sai Kung, with the next earliest on 13 April 2003. Since 2000 there have been few counts in spring higher than two, and the highest is ten on 28 April 2013. This is lower than the period before when flock sizes up to ten were regularly noted, the highest being 15.
Passage is of a similar strength in autumn, with the highest count since 2011 being 11, though most records concern four or fewer. This contrasts with the situation up to 2000 when autumn passage was stronger than that in spring and flocks of 10-30 were recorded in most years, with a peak of 50 at Aberdeen CP on 17 August 1997. The latest autumn record is of one on Po Toi during 12-15 November 2020, with the previous latest being one there on 31 October 2010.
In the period 1978 to 2000 the mean peak weekly aggregate count from the second week of April to the end of May was 3.7 but only 2.2 since, while the mean peak weekly aggregate count from the first week of August to the end of October was 10.9 but only 6.3 since. Against a backdrop of increasing observer activity and for what is a highly visible species, these figures suggest at least a 40-50% decline in the number of birds passing through HK.
The decline in the summer months may be greater. From 1978 to 2000 the number of weekly periods in June and July in which Black Baza was recorded was 65, while in the period 2001 to 2020 this figure was 18, and it is no longer recorded annually in this season. Figure 1 compares the pre and post year 2000 occurrence patterns.
The only historical record traced for Guangdong is of a female obtained in the north on 9 October (Mell 1922). In HK it was first recorded in 1972 (Viney 1973). Following a further record in 1976, it was reported in increasing numbers each year until the end of the century. Black Baza is an easily detected raptor species and, while it may have been overlooked in the past, it seemed at the time likely that the increase in HK was related to a range extension, combined locally with woodland maturation. In the context of this and the species’ widespread presence in south China, it is difficult to account for the decline that has occurred subsequently.
BREEDING
In the 1990s birds were reported almost annually giving aerial display flights from 21 April to 6 June, but there was only one confirmed breeding record: a nest with two almost fully-fledged young in a pine tree at Sha Tau Kok on 12 July 1989 (Croft 1990). Since then, display flight has been noted once, nesting at least twice (at Man Kam To in 2017 and Kong Nga Po in 2022), and adults with juveniles (indicating local breeding) once, in mid-July 2014.
BEHAVIOUR, FORAGING & DIET
The only food items reported are a Changeable Lizard Calotes versicolor, noted once in May, and large fleshy insects such as cicadas, mantids, crickets and dragonflies. One was observed at dusk in spring chasing Short-nosed Fruit Bats Rousettus leschenaulti emerging from a roost (Ades 1993).
Migrants were often seen in flocks prior to its decline here. Perches prominently for periods of time on leafless trees.
RANGE & SYSTEMATICS
Breeds from southern foothills of Himalayas to south China and south through much of Indochina; most Chinese birds are migratory; resident in south India, Sri Lanka, Malay peninsula, and a winter visitor to Sumatra and Java (Clark and Kirwan 2020). In China, a summer visitor to the southern half of the country (Liu and Chen 2020).
Three subspecies are recognised, of which A. l. syama occurs from the Himalayas to south China, including HK. The nominate occurs from south India to south Myanmar and west Thailand, while A. l. andamanica is restricted to the Andaman Islands.
CONSERVATION STATUS
IUCN: Least Concern. Population estimated at 10,000 to 50,000, decreasing.
Figure 1.
Ades, G. (1993). Wildlife Windows. Porcupine! 6: 4-5.
Clark, W. S. and G. M. Kirwan (2020). Black Baza (Aviceda leuphotes), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.blabaz1.01
Croft, N. (1990). Nesting Black Bazas at Sha Tau Kok. The first breeding record for Hong Kong. Hong Kong Bird Report 1989: 141.
Liu, Y. and Y. H. Chen (eds) (2020). The CNG Field Guide to the Birds of China (in Chinese). Hunan Science and Technology Publication House, Changsha.
Mell, R. (1922). Beitrage zur Fauna sinica. Archiv fur Naturgeschichte 88 (10): 1-100.
