Kei Ling Ha Biodiversity
by Thomas Gomersall
Despite being roughly 10 minutes’ drive away from Sai Kung, Kei Ling Ha for the most part goes unvisited by the crowds of day-trippers and tourists that flock to Sai Kung on a regular basis. Much to the benefit of its wildlife and the relief of the few people who do live here, this has resulted in it being one of the most peaceful, quiet, yet accessible natural areas in the Sai Kung area.
Straddling the shores of Three Fathoms Cove, Kei Ling Ha boasts a wide range of habitats, the most noticeable of which being its large intertidal mangrove swamp. Fed by fresh water from a local stream and containing, mudflats, rocky shores and no small amount of mangrove cover, this habitat alone is home to a vast array of species from fish to snails to crabs to water birds. But the forests and abandoned farmland surrounding the swamp also support plenty of species, some of them so rare they have seldom been seen anywhere else in Hong Kong.
Grey Mullet (Mugil cephalus): Able to live in both fresh water and the sea, one of Hong Kong’s most common fish finds an ideal habitat in the estuary of Kei Ling Ha. Individuals can be seen leaping from the water and shoals. They also congregate where the stream flows into the estuary. In the winter, large numbers of them will gather in the waters surrounding the Sai Kung peninsula to spawn, although recent unstable temperatures as a result of climate change have been leading to the deaths of up to 25 per cent of all Hong Kong-born fry per year. Plastic pollution is another problem affecting this species. A study in 2018 by the Education University of Hong Kong found that 60 per cent of wild grey mullet examined had microplastics in their digestive systems, with one fish having swallowed 80 pieces.
Grass Puffer (Takifugu niphobles): Wading through the shallows of a mangrove swamp at low tide may not be everyone’s idea of fun, but it’s probably one of the best ways to spot this odd little fish as it speeds away over the sand. Like most pufferfish, when faced with a predator it will inflate its body to make itself seem bigger, and has a highly potent neurotoxin in its intestines that can kill even humans. However it also has another highly unusual behaviour. Along certain beaches during the breeding season, large groups of grass puffers will gather offshore during high tide, then ride a wave onto the beach itself to spawn before returning to the sea. This behaviour has never been seen in any other pufferfish species.
Common Mudskipper (Periophthalmus cantonensis): Another fish frequently seen at low tide is the common mudskipper. Possessing the rare ability among fish to breathe out of water as well as in it, common mudskippers are often found resting on the mudflats but when threatened, can use their tails to flick themselves across the mud away from danger (hence their name). A useful defense strategy in the all-too common event that the local egrets decide to have mudskipper for dinner. When not in such a hurry, they will also use their strong pectoral fins to drag themselves from one place to another.
Pointed-scale Pit Viper (Protobothrops mucrosquamatus): One of Hong Kong’s rarest snakes, the pointed-scale pit viper has only been recorded in two places within the Sai Kung area, including Kei Ling Ha. It lives on hillsides and abandoned farmland, where it hunts for frogs, lizards and small rodents. Although an aggressive and highly venomous snake, its rarity and largely nocturnal lifestyle mean that there are no known snakebites from this species in Hong Kong.
Mangrove (Kandelia obovata): Being so common in Kei Ling Ha, it’s not hard to believe that this is Hong Kong’s most widespread species of mangrove. Between May and July, it produces white, star-shaped flowers and in autumn produce pen-shaped seeds. When ready, these seeds drop into the water at high and float upright so they can be buried in the sand in the perfect position when the water levels go down again. More amazingly, these seeds can alter their density to control how easily they float or sink. For example, if a seedling does not manage to establish itself in one site, it can change its density so as to be light enough to be carried somewhere else by the water.
