The Black-naped and the Roseate Tern

I never had an interest in birds, but since I saw a white-bellied sea eagle near Shek Kwu Chau I have become interested at least in the big raptors. But there are also a lot of seabirds that form part of the ocean ecosystems even in Hong Kong.
And on a recent ferry ride in South Lantau I was treated to a great spectacle of 2 beautiful species of seabirds, the Roseate Tern (Sterna dougallii) and the Black-naped Tern (Sterna sumatrana).

I only had my smartphone with me so I shot this slow-mo footage of the terns ducking and diving behind the ferry and occassionaly plunge-diving into the water at high speed and then flying up again with small fish in their beaks.

Along for the ferry ride were three birders with huge telezoom cameras and I thought at the time “I bet these guys are with the HK Bird Watching Society. I must check their forum page later to see if they post the images…” – I haven;t found them yet, but in the meantime I found these stunning images on th HKBWS Forum which are well worth a look.

The Black-naped Tern has white forehead and crown with black nape extending through the eyes. It is an oceanic bird mostly found in tropical and subtropical areas of the Pacific and Indian Oceans and rarely found inland. It frequents small offshore islands, reeds, sand spits and rocky cays, feeding in atoll lagoons and close inshore over breakers, but sometimes also far out at sea. The diet is mainly small fish and they will almost always forage singly by shallow plunge-diving or surface-diving. The breeding season varies depending on locality, usually forming small colonies of 5 to 20 pairs, but sometimes up to 200 pairs. Colonies are often formed on unlined depression in the sand or in gravel pockets on coral banks close to the high tide line. In Hong Kong It can be seen over the sea and aroundcoastal areas in the summer.

The Roseate Tern has white underparts with pink, red bill and legs. It is a cosmopolitan species occurring all the way from the Atlantic coast of Ireland to Australia, although it is split into 3 races by geographical areas. In Hong Kong it can be seen over the sea and around coastal areas of northeastern and southern waters in the summer. According to the WWF, the Roseate Tern is now a rare visitor to Hong Kong with only 10-20 terns coming to Hong Kong, so it seems I was quite lucky to see some of them!

During the summer months from May to September, the Roseate Tern, the Black-naped Tern and the Bridled Tern regularly come to breed on the small and remote rocky islands in eastern and southern of Hong Kong waters. In the last 10 years between 2001 and 2010, summer population of the 3 tern species at these breeding sites ranged at 270 to 990, or 570 on average.

There are a lot of keen bird-watchers in Hong Kong, so there is no shortage of information and photographs of terns in Hong kong on the web, so if you are interested in finding out more about these birds, have a look at:

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Suspected Mui Wo Shark is Actually a Dolphin

Marine police on Saturday (7th May 2016) searching for a shark in Silvermine Bay after a beach-goer reported that he might have seen a shark outside the shark net. The life guards raised the red flag and a police launch and government flying service helicopter were dispatched. But witnesses interviewed by Apple Daily also suggested it may have swum more like a dolphin than a shark. Apple Daily posted a video on their site  here. You can see the “shark” at the 1:00 minute mark. It’s definitely a dolphin.

Newborn dolphin dies at Ocean Park; 2 more found dead on Hong Kong beaches

 A newborn dolphin, a small marine cousin of the dolphin, died at Ocean Park last night, where it had been born just 73 hours earlier. Its death came on the same day that two other finless porpoises were revealed to have been found dead on the city’s beaches.

The dead calf’s mother was said to have had a difficult labour, and her baby, a female, immediately displayed an abnormal swimming pattern. The theme park said she also found it difficult to stay alongside her mother when she was not suckling.

Necropsy results show the calf’s stomach was empty, and about 25 per cent of her lungs were not fully expanded. The theme park said it was not uncommon for dolphins to die in infancy, citing a previous study of dolphins in Western Australia, which showed 44 per cent of calves do not survive to three years of age.

Meanwhile, Mui Wo resident Leslie Parker said her son and his friend found the body of what was initially thought to be a seal or sea lion on the rocks near Lower Cheung Sha beach on Wednesday.

Officers from the Agriculture, Fisheries and Conservation Department and Ocean Park’s Cetacean Stranding Response Team visited the site yesterday evening to conduct an autopsy. They removed the carcass for further examination.

A dolphin, which lacks a dorsal fin, may appear similar to a sea lion, said Dr Samuel Hung Ka-yiu, chairman of the Dolphin Conservation Society. However, the porpoise has a smoother skin, with no hair, and it has a tail, while the sea lion has flippers. The species is considered vulnerable by the International Union for Conservation of Nature.

“The six months between December and May have always been the time of the year when most strandings of dolphins are reported,” said Hung, adding that gillnet fishing was usually the cause of dolphin deaths in Hong Kong waters.

Yesterday morning, police received another report of a dead finless porpoise – this time a 158cm-long adult, which was discovered at a beach off Tai Wan Tau Road, Tseung Kwan O.

The Ocean Park response team were again sent to the scene and took a sample to find out the cause of death. A spokeswoman described it as “severely decomposed”, with signs of having been strangled by a fishing net. There were also bruises on its tail.

There were 32 reports of finless porpoise strandings last year.


Reported by the SCMP ON 2nd April, 2015

Noctiluca scintillans – Jekyll & Hyde of Plankton

This week red tides have been reported all across the western half of Hong Kong including Discovery Bay, Peng Chau, Mui Wo, East and West Lamma Channel. The culprit was once again the plankton species Noctiluca scintillans – neither fully plant not fully animal. It’s a single-called organism from a group called dinoflagellates. They consist of a bubble-shaped cell with two whips called flagella – that propel them through the water.

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Though Noctiluca eats other plankton it doesn’t always kill what it eats: sometimes it leaves algae intact and stores it in little bubbles in its body (cell) where the algae make sugars that leak out and feed Noctiluca while the waste produced by Noctiluca feeds the photosynthesis of the preyed on algae – a process known to most as symbiosis and also found in tropical corals. However Noctiluca can also just eat the algae. Why and how it decides to eat or farm the algae is not really clear.
Noctiluca is a well known and non-toxic local red tide species and its occurrence is not necessarily a sign of pollution, but entirely natural. What is perhaps not natural is the size of the bloom, though. This could well point to agricultural fertiliser run-off and sewage effluent particularly from the fast growing population of the Pearl River Delta (PRD).

Images of the recent red tide at Lantau
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Noctiluca has however a redeeming feature – bioluminescence! That beautiful sea sparkle of iridescent blue that night divers in the tropics often sea or beach goers see in the breaking waves at night. So blood-red tides on the one side and beautiful sea sparkle on the other, Noctiluca is the Jekyll and Hyde of HK’s marine environment.

Long exposure image of a Noctiluca scintillans patch (cm via WikiCommons):

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If you would like to know more about Actual toxic red tides in Hong Kong here is a little TV news documentary from 2013 I found on YouTube: