Sep 12, 2020
Nam Sang Wai Biodiversity
by Thomas Gomersall
Lying within walking distance of Yuen Long, Nam Sang Wai is the perfect place for birdwatchers because of its many diverse habitats that make the Deep Bay area such a haven for birds. On one side of Nam Sang Wai road: the Shan Pui river, which at low tide hosts many of the common (and less common) wetland birds of Hong Kong like the black-faced spoonbill, Chinese pond heron and garganey. On the other side: a patchwork of fishponds and tall grasses, the perfect hiding place for shy reedbed birds. For some added quaintness, just a short walk from Yuen Long MTR lies the Nam Sang Wai ferry pier, where passengers can be rowed across the river in a wooden boat to marvel at the pristine ponds and cormorant-laden trees on the other side.
Black-headed Gull (Chroicocephalus ridibundus): The name ‘black-headed gull’ may seem misleading to those who first see this bird in Hong Kong during its winter migration, as the closest individuals spotted here usually come to having a black head is a small smudge of black behind the eye. However, this is only its winter plumage and it does develop a darker head during the breeding season and sometimes even as early as December (Viney et al, 2005, p. 120; Tipper, 2016, p. 64).
Black-browed Reed Warbler (Acrocephalus bistrigiceps): The tall grasses and reedbeds of Nam Sang Wai provide ideal habitat for a wide range of songbirds, including the black-browed reed warbler, named for the distinctive black strip over its eye. This bird is a common passage migrant and scarce winter visitor to the reedbeds of Deep Bay. It tends to remain hidden deep within the reeds, but can sometimes be spotted perching on top of them to sing during the spring (Tipper, 2016, p. 116).
Eastern Marsh Harrier (Circus spilonotus): As well as songbirds, the reedbeds of Nam Sang Wai are also an ideal spot for the Eastern marsh harrier, whose preferred habitats are well-vegetated wetlands. A common winter visitor to Deep Bay, this raptor is best identified in flight by its unique hunting technique, in which it will fly slowly over the ground holding its wings in a shallow V-shape (Tipper, 2016, p. 36).
Black-winged Stilt (Himantopus himantopus): Even for a wading bird, the black-winged stilt has extraordinarily long legs — more than half the length of its body (WWF Hong Kong, 2011)– which allow it to forage in deeper water than many other waders (Hong Kong Wetland Park, 2019). It is found in fresh or brackish water and has a particular preference for drained fish ponds (Tipper, 2016, p. 42; Viney et al, 2005, p. 86). Although it is most common in Hong Kong during the winter, unlike many other waterbirds, a small number will also breed here during the summer in mounds of grass or depressions in the ground close to the water. The female lays up to four eggs and both parents will incubate and guard them vigorously, even physically attacking predators that come too close to the nest (WWF Hong Kong, 2011).
Asian Barred Owlet (Glaucidium cuculoides): Owls are typically strictly nocturnal birds and this is certainly true for the majority of Hong Kong’s owl species. The Asian barred owlet, however, slightly breaks the mould, as it is partially diurnal and can sometimes be seen and heard calling during the day. A common resident in the central and northern New Territories, its call is a rapid “oo-oo-oo” that gradually rises in volume and then finally falls to a lower pitch (Tipper, 2016, p. 80).
References:
· Hong Kong Wetland Park, Black-Winged Stilt, [website], 2019, https://www.wetlandpark.gov.hk/en/biodiversity/beauty-of-wetlands/wildlife/himantopus-himantopus (Accessed: 9 October 2019).
· Tipper, R. 2016. A Naturalist’s Guide to the Birds of Hong Kong, John Beaufoy Publishing, United Kingdom. 36pp., 42pp., 64pp., 80pp., 116pp.
· Viney, C., Phillipps, K. and C.Y. Lam. 2005. The Birds of Hong Kong and South China, Information Services Department, Hong Kong SAR Government, Hong Kong. 86pp., 120pp.
· WWF Hong Kong, Record numbers of breeding Black-winged Stilt at Mai Po Nature Reserve, [website], 2011, https://www.wwf.org.hk/en/news/?4480/Record-numbers-of-breeding-Black-winged-Stilt-at-Mai-Po-Nature-Reserve (Accessed: 9 October 2019).
