The environmental group Green Power has discovered the Asiatic Blood Tail (Lathrecista asiatica) at Tung Chung River. This is the first time this dragonfly species has been recorded in Hong Kong. This discovery was made during a regular dragonfly survey at the end of August, in a wetland near the estuary of the Tung Chung River, in southern Tung Chung Bay on Lantau Island.
Mr Henry Lui, Senior Conservation Manager of Green Power described the male Asiatic Blood Tail as having a face that is milky white in colour, brown spots on its forehead, a brown thorax, and a bright red abdomen with a black tip. The one that was recorded this time had a distinct greyish-white powdery covering on its thorax, indicating that it was a mature male. The Asiatic Blood Tail is the only species of the Genus Lathrecista of Family Libellulidae. It is found widely across tropical Asia and northern Australia, with sightings recorded in Yunnan, Hainan, and Taiwan as well. It typically inhabits lowlands below 500 metres above sea level, and its habitats include marshes associated with ponds and streams. Tung Chung River basin, where it was recently discovered, is exactly its typical habitat.
Concerns over impact from future residential development on dragonfly habitats
Mr Henry Lui, however, expressed concern that the location of this recent Asiatic Blood Tail discovery happens to lie on the outskirts of an area classified as a Residential (Group C) development zone under the Tung Chung Valley Outline Zoning Plan. Worried that future residential development would impact the dragonfly’s habitat, he urged authorities to strengthen conservation efforts of the natural habitats in the area. In particular, land rezoning involving wetland habitats should be avoided.
Mr Henry Lui added that the Tung Chung River is one of Hong Kong’s last remaining large natural rivers. With much of its natural landscape, from the origin to the estuary of the river and the adjacent bay, having been retained, it holds significant conservation value. The Tung Chung River and the surrounding wetland environments have long nurtured many dragonfly species. Since 2012, Green Power has recorded 61 dragonfly species through the dragonfly surveys it has been conducting in the Tung Chung River basin, accounting for nearly half of all the dragonfly species in Hong Kong. Some of these species have conservation value, including the Guangdong Hooktail (Melligomphus guangdongensis) and Mangrove Skimmer (Orthetrum poecilops), both of which are listed as “Vulnerable” on the International Union for Conservation of Nature (IUCN) Red List. In addition, all four species of Family Platystictidae recorded in Hong Kong can be found in the valley of the upper reaches of Tung Chung River.
Mr Henry Lui expressed that with the recent first-time discovery of the Asiatic Blood Tail, it can be said that Tung Chung River is one of the most important local dragonfly habitats, and also confirms its high ecological value. He hopes that the impact of Tung Chung New Town Expansion (West) on the habitats in the river basin can be minimised, with the natural landscape of the Tung Chung River, its estuary, and Tung Chung Bay preserved as much as possible.
Potential impact of global warming on distribution
Mr Henry Lui also pointed out that the Asiatic Blood Tail is mainly active in tropical regions near the equator, with sporadic recordings in locations towards the north such as Hainan and southern Taiwan. The species are also being recorded in Hong Kong despite the fact that Hong Kong is situated between these two regions; this could further indicate a possible northward expansion trend in the species’ distribution. This is believed to be related to global warming, though the future frequency of local Asiatic Blood Tail sightings remains to be observed.
