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:


Sea Eagles and the planned Waste Incinerator at Shek Kwu Chau

On a recent boat trip along southern Lantau I noticed a large bird of prey soaring in the distance. If you live in HK you know that we have thousands of black kites that soar overhead pretty much everywhere including the financial district of Central. So normally the sight of a bird of prey soaring overhead is commonplace and not worthy of note. I would not have thought more of it. But it struck me that this bird seemed bigger and the closer the boat got, the bigger it seemed. A lot bigger than a black kite! Once we got close enough and passed under it I saw it had a wide white triangular shape covering its head, belly and part of the underside of the wings. Looking it up in my copy of ‘Birds of Hong Kong and South China’ I managed to identify it as a white-bellied sea eagle (Haliaeetus leucogaster). Sea eagles in Hong Kong? That surprised me.
I will confess that I have never been particularly interested in birds. I could never understand the fascination bird watchers have with these animals, especially the small birds that in my opinion “don’t do much”. But like any subject, it’s finding the right angle to enter a topic that counts and for me that’s always been the marine environment. So an impressive sea eagle may well lead me to an interest in birds eventually!
There would be little point in recounting general facts about this beautiful creature when you can get all this from Wikipedia’s article on white-bellied sea eagles. But I will mention the size because it impressed me: the female is slightly larger than the male, and can measure up to 90 cm (35 in) long with a wingspan of up to 2.2 m (7 ft), and weigh 4.5 kg (10 lb). Up to 2.2m wingspan! I needed to know more…
Naturally I went looking for information and records of these sea eagles in Hong Kong.

Here is a nice YouTube clip apparently from Hong Kong of a juvenile white-bellied sea eagle soaring over the water:

Beasts of Hong Kong is a great blog with a post on the sea eagle . It has some surprising info: I had no idea that the sea eagles nested on Lantau until Disney and it’s carbon-footprint busting nightly fireworks came along.

Other interesting bits:

  • according to the HK bird watching society Hong Kong is the only place in China known to host a regular population
  • white-bellied sea eagles are especially fond of fish and snakes and they have amazing skills of flight and control as it they snatch their prey from the surface of the water
  • in 2009 there were 15 breeding pairs (30 adults) in Hong Kong the AFCD reports
  • in 2006 the Hong Kong Post issued a 10 white-bellied sea eagle postage stamp
10 cent Hong Kong postage stamp featuring the white-bellied sea eagle
10 cent Hong Kong postage stamp featuring the white-bellied sea eagle

Uniquely interesting for me is that the AFCD study published in 2010 also located a breeding pair on the island of Shek Kwu Chau. Below is the map from the study showing breeding pair locations.

Territories (green) and breeding pairs (red) of white-bellied sea eagles in Hong Kong (AFCD, 2010).

Shek Kwu Chau is the Island the government is planning to turn into a giant waste incineration facility amid strong opposition from green groups and the Hong Kong Clean Air a Network (CAN). So you just got another reason to oppose the project, if air pollution and inefficient waste management were not enough…

The AFCD study found that the population of White-bellied Sea Eagles in Hong Kong seemED healthy. According to the study, “the White-bellied Sea Eagle’s decline […in other regions…] is mainly due to threats such as human disturbance, habitat destruction, shooting and poisoning (Ferguson-Lees and Christie, 2001). In Hong Kong, thefts of eggs from nests and disturbance such as grass cutting have caused breeding failures of White-bellied Sea Eagles in the past (Taylor, 1933). With the enforcement of the Wild Animals Protection Ordinance (Cap. 170), direct human disturbance of the birds is now prohibited. Besides, as most of the nests are located in protected or remote areas, their nesting sites are relatively free from development pressures.” (AFCD report).

I wonder for how long the population of white-bellied Sea Eagles will be healthy if we build super-incinerators on their nesting grounds…

And finally a very recent YouTube clip of a white-bellied sea eagle over Stanley from March 2014.

(Featured image: White-Bellied Sea Eagle by Richard Fischer, subject to attribution license)