Japanese Night Heron Gorsachius goisagi 栗鳽
Category I. Accidental.
IDENTIFICATION
Dec. 2019, Martin Hale. First-winter.
48-49 cm. Small and stocky with short, decurved bill. Young birds such as this are dull brown overall with small white spots on mantle, rather variegated scapulars and wing coverts, relatively plain and grey-brown crown and barred sides to the head; legs are dull greyish or greyish-green.
Dec. 2019, Michelle and Peter Wong. First-winter.
In flight has broad buffish tips to blackish flight feathers and warm brown greater primary coverts.
Adults are dull orange-brown above, rather warmer on the sides of head and neck; underparts buff streaked dark. Lacks blue lores.
VOCALISATIONS
Not heard to vocalise in HK and appears to do so very rarely away from the breeding grounds.
DISTRIBUTION & HABITAT PREFERENCE
Has occurred at scattered sites across HK where there is sufficient vegetative cover.
OCCURRENCE
1972: one at Pok Fu Lam during 3-4 December (Webster and Viney 1973).
1974: one at Mount Kellett Road, The Peak on 10 November.
1977: one at Cassino Lines, near San Tin on 16 November (though apparently present for a week prior).
1982: one at Ho Sheung Heung on 20 April.
1988: an adult that flew into a wall of the HK Polytechnic University, Hung Hom on 19 April was taken into care and released at Tai Po Kau on 21st.
2014: Pak Tam Au during 15-16 December (apparently present 7-10 days earlier).
2019: Pak Tam Chung from 27 November to 24 December.
BEHAVIOUR, FORAGING & DIET
Some birds have been rather tame and allowed close approach. The bird at Pak Tam Chung was observed to eat worms that it appeared to locate under the ground aurally. During foraging it would fly to adjacent woodland edge to rest and digest, or when flushed.
RANGE & SYSTEMATICS
Monotypic. Breeds in southern Japan in Kyushu, Shikoku and the southern part of Honshu (Brazil 2018), and has bred on Cheju, South Korea (Oh 2010). Winters from the Ryukyu Islands to the Philippines (Martínez-Vilalta et al. 2020). In China, a rare migrant through coastal provinces, including Taiwan (Liu and Chen 2020).
CONSERVATION STATUS
IUCN: VULNERABLE. Population size 5,000 to 5,999 and decreasing due to deforestation in breeding areas and trapping on wintering grounds.
Brazil, M. (2018). Birds of Japan. Helm, London.
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.
Martínez-Vilalta, A., A. Motis, and G. M. Kirwan (2020). Japanese Night-Heron (Gorsachius goisagi), 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.janher1.01
Oh H. S., Y. H. Kim and N. K. Kim (2010). First breeding record of Japanese Night Heron Gorsachius goisagi in Korea. Orn. Science 9(2): 131–134.
Webster, M. A. and C. A. Viney (1973). Report on the birds 1972. Hong Kong Bird Report 1972: 4-42.
