Cinnamon Bittern Ixobrychus cinnamomeus 栗葦鳽
Category I. Scarce passage migrant and summer visitor, rare in winter; occurs in vegetated freshwater wetland areas.
IDENTIFICATION
Jan. 2022, Michelle and Peter Wong.
40-41 cm. Identification is discussed in Leader (1996). Bill relatively short and dagger-like, similar to Von Schrenck’s Bittern. Adult male has bright chestnut crown through mantle, paler and more orange than Von Schrenck’s. Underparts sandy-brown with indistinct mid brown gular stripe.
May 2019, Kinni Ho. Male.
Upperwings of male are chestnut, slightly paler on the coverts; underwing chestnut-grey. Red facial skin in breeding season.
Apr. 2021, Kinni Ho.
Adult female has grey wash to upperparts, pale spots on coverts and prominent stripes down neck. Primaries and secondaries warmer than dark upperwing coverts. Underwing chestnut-grey.
Immatures are mid brown above with fine pale streaks or large sandy fringes forming spots on coverts. Stripes on neck well-marked. Young female darker than young male.
VOCALISATIONS
The song can occasionally be heard in spring, usually from reed marsh.
The flight call is a fairly deep and repeated ‘kok-kok-kok…’
DISTRIBUTION & HABITAT PREFERENCE
Cinnamon Bittern occurs mainly in damp lowland areas with dense vegetation, in areas of freshwater marsh and in reed beds (though it appears less tied to reeds Phragmites than is Yellow Bittern). It is thus mainly recorded in the Deep Bay area and at Long Valley. However, migrants also occur at a wide variety of other sites near water, including urban parks. Historically, the highest numbers occurred in areas of rice cultivation. May also be recorded in damp forest areas on passage.
OCCURRENCE
Figure 1 indicates that small numbers of Cinnamon Bittern winter here. Spring migration occurs from at least the final week of March, with main passage extending to at least the last week of May and the highest single-site count being four. There are records throughout the summer period, but only one confirmed instance of breeding since 1958.
Autumn passage gathers momentum from the final week of July and the main passage occurs from the final week of August to the third week of October. Migrants continue to be noted until November (one was found dead at the former airport at Kai Tak on 11 November 1975), though other records at this time may refer to wintering birds. By far the highest count is of ten birds at Tai Yuen, near Mai Po on 19 May 1971, with the next highest being six at Pui O on 25 May 1985 and 30 May 1986.
Vaughan and Jones (1913) stated that Cinnamon Bittern was a summer visitor from April to October with one winter record; it was said to nest in ‘many favoured spots’, and at Kong Mun, near Macau it occurred in ‘large numbers together with Ixobrychus sinensis and Dupetor flavicollis’. Dove and Goodhart (1955) found it ‘a fairly common summer visitor, always in paddy fields and not marsh or mangrove swamps.’ Such a habitat preference applied elsewhere in South China (La Touche 1931-34).
Dove and Goodhart also stated that the call (presumably the song) was a familiar sound in Long Valley, though they considered numbers to be somewhat variable, with 16 sight records in 1952 and only five in 1953; in contrast, five records from the same observer would be unusual now. Herklots (1967) stated only that it was ‘much less common than the Yellow Bittern and numbers vary from season to season’, and that it ‘must breed…but no nests have yet been found’. This perhaps indicates that a decline had already set in by this time. It seems certain, however, that the disappearance of rice cultivation from HK led to a change in this species’ status from that of a breeding summer visitor to that of a passage migrant.
BEHAVIOUR, FORAGING & DIET
No observations.
BREEDING
There is one confirmed instance of breeding since 1958: an adult with four eggs (the first of which hatched on 8 July) at Hong Kong Wetland Park on 7 July 2018. Displaying males and birds in song in reed marsh have also been recorded from late March to mid-June, and young juveniles, suggesting breeding on site, have been recorded at Kam Tin and Lok Ma Chau MTRC Ecological Enhancement Area on 20 August and 11 September.
RANGE & SYSTEMATICS
Monotypic. Breeds from northern India and Nepal east to China as far as the Bay of Bohai; winters near the coast in the Indian subcontinent, and in Indochina, south China, southeast Asia, the Philippines and Indonesia (Martínez-Vilalta et al. 2020). In China breeds in lowland non-desert areas from Yunnan northeast to Liaoning, and winters in the southwest, Hainan and Taiwan (Liu and Chen 2020).
CONSERVATION STATUS
IUCN: Least Concern. Population trend stable.
Figure 1.
Dove, R. S. and H. J. Goodhart (1955). Field observations from the Colony of Hong Kong. Ibis 97: 311-340.
Herklots, G. A. C. (1967). Hong Kong Birds (2nd ed.). South China Morning Post, Hong Kong.
La Touche, J. D. D. (1931-34). Handbook of the birds of Eastern China Vol. 2. Taylor and Francis, 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). Cinnamon Bittern (Ixobrychus cinnamomeus), 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.cinbit1.01
Vaughan, R. E. and K. H. Jones (1913). The birds of Hong Kong, Macao and the West River or Si Kiang in South-East China, with special reference to their nidification and seasonal movements. Ibis 1913: 17-76, 163-201, 351-384.
