Besra 松雀鷹 Accipiter virgatus
Category I. Present all year. Numbers highest in autumn when passage migrants occur in diverse wooded areas and lowest in summer when it breeds in closed-canopy shrubland.
IDENTIFICATION
Oct. 2014, Martin Hale. Adult female.
24-36 cm. Small to medium size accipiter with relatively short wings and long tail. The longest primaries are p4 and p3. Underparts of adults such as this female are boldly and contrastingly marked in comparison with Japanese Sparrowhawk, but similar to Crested Goshawk (DeCandido et al. 2014). The yellow cere has a greenish tinge.
Adult female has variegated underparts with elongated and broad blackish streaks on the breast and a broad blackish mesial. The flanks and belly broadly are barred dull chestnut-brown, and the upper belly may be solid chestnut-brown.
Nov. 2014, TAM Sik Pang. Adult male.
Adult male upperparts are medium-dark grey, often with a purple wash, while the underparts are broadly barred dull chestnut-brown with narrow pale bars. Throat white with narrow to broad dark mesial, chest has diffuse greyish streaks. Iris deep red.
Aug. 2014, TAM Sik Pang. Juvenile.
Juvenile has broad blackish tear drop-shaped marks that contrast markedly with brownish bars and marks on the rest of the underparts, a broad very dark mesial, narrow warm buff fringes to upperparts in fresh plumage and a yellow iris.
Sep. 2014, Y. W. Fong.
Differences from Japanese Sparrowhawk, with which it is most likely to be confused, were discussed by Leader and Carey (1995). Same-sex Besra is longer in wing and tail than Japanese Sparrowhawk, although tail length overlaps between male Besra and female Japanese. The dark tail bars of Besra are generally approximately equal in width to or slightly wider than the pale bars, the mesial stripe is broader, the wing is less pointed and the primary projection shorter, the tips falling less than halfway down the tail. In addition, the upperparts of females and juveniles are browner than those of Japanese Sparrowhawk.
VOCALISATIONS
The call most often heard is a short ‘keee-keee-kee-kee-kee’ that falls in pitch and volume. It is unclear, however, how this differs from similar calls given by Crested Goshawk and Japanese Sparrowhawk, though it may be lower in pitch. Note also that this phrase is one of the most frequently uttered by mimetic Orange-bellied Leafbird.
Also, a drawn out ‘kyee-kyee’.
DISTRIBUTION & HABITAT PREFERENCE
Besra is recorded throughout the year in widespread areas of closed-canopy shrubland, forest and fung shui woodland, particularly in the central and eastern New Territories and on HK and Lantau islands. It is much more widespread outside the breeding season when it is also found in areas of marsh, fish ponds, mangroves and agricultural land in the Deep Bay area and other parts of the New Territories, with autumn sightings on small islands such as Po Toi, Chek Lap Kok, Cheung Chau and the Soko Islands. In the non-breeding season females are more commonly recorded in open-country habitats and males in closed-canopy habitats.
Breeding undoubtedly occurs in widespread areas of closed-canopy shrubland and forest throughout the New Territories, HK Island and on Lantau. The 1993-96 breeding bird survey recorded Besra in 2.6% of squares, while the later 2016-19 survey recorded it in 4.2% of squares. This may be due to vegetation succession, though it may also be partly due to increased observer familiarity with the species. The percentage of squares in which it was recorded in the winter atlas surveys was similar, at 2.9% in 2001-05 and 2.7% in 2016-19, both periods when identification criteria were more widely appreciated.
OCCURRENCE
Figure 1 illustrates the pattern of occurrence since 1999, a period when the critical identification features were generally understood. Besra is more commonly reported than Japanese Sparrowhawk and it is generally considered that both residents and migrants occur. Numbers are highest in autumn when passage migrants, some on active migration, are reported. Main passage is from the second week of September to the first week of November, with no clear peak. On Po Toi, where Besra is not known to breed, it has been recorded from 8 September to 29 November, with further records on 9th and 24 December.
Winter numbers are lower until the end of March, though breeding birds become more visible as early as mid-January, depending on weather and temperature. The higher number reported from the first week of April or earlier reflects spring migration. On Po Toi it has been recorded from 22 March to 23 April, with a further record on 14 May. The highest count is of five birds on 7 April 2020.
Site fidelity was shown by a bird originally ringed at Mai Po as a first year in September 2011 that was retrapped as the same site on 6 November 2020. In addition, a female found injured at Mai Po in early July 1997 and taken into care at Kadoorie FBG was released at Mai Po later the same month and subsequently retrapped there on 10 December 1998.
Due to previous confusion over identification, a male at Tai Po Kau on 8 October 1980 stands as the first adequately substantiated record. A bird shot at Lam Tsuen on 4 March 1933 and published as "Himalayan Sparrow Hawk A. virgatus affinis (?)" (Herklots and Taylor 1933) was considered at the time to match available descriptions of this species.
BREEDING
A pair was observed nest-building at Mount Davis on 19th and 20 April 1988, with the female seen incubating in May; however, the nest was subsequently abandoned (Smith 1989). Nest-building was also observed at Fanling Golf Course on 1 April 2020 and birds were repeatedly seen carrying food toward a fung shui wood at Shuen Wan from 12 May to 19 June in 1999 and 2003 and on 8 August 2009. Displaying birds have been recorded in the first five months of the year (mostly in March and April), September, November and December. In general, however, the secretive habits of this species in the breeding season mean there are few breeding records.
BEHAVIOUR, FORAGING & DIET
Has been observed hunting bats, Striated Heron, Black-capped Kingfisher, snipe Gallinago sp., Chestnut Bulbul, Blue-winged Minla, Silver-eared Mesia, Hair-crested Drongo, Barn Swallow, White-shouldered Starling and wagtails. Successful captures of Spotted Dove, Arctic Warbler, Swinhoe’s White-eye, Crested Myna, Eurasian Tree Sparrow and Chinese Bulbul have been recorded.
Males or pairs can be seen in display over closed-canopy shrubland or forest in early spring, soaring and calling. Migrants can be seen in widespread areas soaring with other raptors.
RANGE & SYSTEMATICS
Breeds in west and east India, northern Pakistan and the Himalayas east into west, central and south China, northern parts of Indochina, the Philippines and the Greater and Lesser Sundas (Clark and Marks 2020). In China resident in the southern half of the country (Liu and Chen 2020). Based on the pattern of occurrence in HK some populations are migratory.
Polytypic species with a number of discrete populations. Birds in HK are A. v. affinis, which breeds from west Himalayas to central China and Indochina.
CONSERVATION STATUS
IUCN: Least Concern. Population trend decreasing.
Figure 1.
Clark, W. S. and J. S. Marks (2020). Besra (Accipiter virgatus), 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.besra1.01
DeCandido, R., N. Chukiat, M. Siponen, K. Sutasha A. Pierce, J. Murray and P. D. Round (2014). Flight identification and plumage descriptions of six Accipiter species on southbound migration at Khao Dinsor, Chumphon province, Thailand. BirdingAsia 21: 52-62.
Herklots, G. A. C. and M. Taylor (1933). Notes and Comments. Ornithology. Hong Kong Naturalist 4: 71-75.
Leader, P. J. and Carey, G. J. (1995). Identification of Japanese Sparrowhawk and Besra. Hong Kong Bird Report 1994: 157-169.
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.
Smith, S. (1989). Notes on the first recorded breeding attempt of Besra in Hong Kong. Hong Kong Bird Report 1992: 131-133.
