Endangered waterbird spotted in Hong Kong

A routine morning bike ride at Tai Lam Country Park on 20 January turned into an unforgettable moment for birdwatcher John Chow Kwok-pun. He spotted what he recognised as a female merganser bird at a stream near Kat Hing Bridge, but could not identify it at the time because the bird was diving and swimming in the reservoir.

“My first impression was that it was likely to be a female Red-breasted Merganser, a rare but regular species in Hong Kong,” said Chow. “However, its presence in freshwater habitat raises suspicion that it may not be this species, but one of two that prefers freshwater habitat.”

Three days later, Chow returned to the bridge along with other bird watchers.

“I could see that the merganser has fine gray scales on the chest and flanks, ruling out Red-breasted and Common Mergansers,” said Chow. “The overall features fall within those of a Scaly-sided Merganser, a previously unrecorded species in Hong Kong.”

It turned out to be the first Scaly-sided Merganser ever spotted in Hong Kong. It is an endangered duck species native to North Asia and the Russian Far East.

"The Scaly-sided Merganser, though first recorded in Hong Kong this year, has been recorded in the region and is considered a rare winter visitor to South China," said Joyee Chan Long-kwan, a fauna conservation officer at the Agriculture, Fisheries and Conservation Department.

The large duck is endemic to the East Asian-Australasian Flyway, a major migratory route for over 50 million waterbirds, according to the East Asian-Australasian Flyway Partnership, which includes the Hong Kong Bird Watching Society.

"Hong Kong is a major stopover point along the bird migration route. The wide variety of local habitats contributes to the diversity of the birds," said Chan.

The Scaly-sided Merganser is on the endangered list of the International Union for Conservation of Nature. There are an estimated 3,600 to 6,800 individuals worldwide and its population is decreasing, according to BirdLife International, a global network of non-governmental organisations specialising in bird conservation.

The Scaly-sided Merganser primarily breeds in Northeast China, Southeast Russia and North Korea where they nest in tree holes near clear-flowing rivers and streams. During the non-breeding season, the merganser winters in Central and Southern China and South Korea, according to the EAAFP.

The female Scaly-sided Merganser at Kat Hing Bridge was accompanied by a Little Egret, nicknamed “Lulu” by photographers.

The two species usually compete for food. While the merganser swam around the stream for fish, “Lulu” was watching closely, hopping from rock to rock to avoid being pushed by the current, waiting for an opportunity to seize the merganser’s catch.

Studies on little egrets reveal that “territoriality is strong" when sharing feeding space with other species, according to HeronConservation, a leading body in global heron conservation.

And after half an hour of wading and diving, the merganser would perch on a nearby cluster of rocks to nap. “Lulu” almost never left her side.

But despite competing for fish, "Lulu" and the merganser were not violent towards each other.

“It is quite interesting to see the partnership of the little egret and the merganser," said Chow.

For passersby, many were curious as to why a huge gathering of photographers was present.

University student Ali Saim and avid mountain biker Nawang Rana were biking when they noticed a horde of photographers stationed at the edge of the stream near the bridge.

Saim, 19, and Rana, 22, got off their bikes to find out why.

“I could only notice the white bird at first because it was much bigger,” said Saim. “I thought that they had come there to only photograph that common egret bird.”

“One of the photographers was kind enough to show me an image of the bird they were photographing and even pointed in its direction,” said Rana.

Apart from the bond between the two waterbirds and the attention they drew, observers have noticed that the merganser has a broken lower bill, exposing its tongue.

"Many experienced birders think the injury was caused by a fish hook that tore the bill apart," said Chow. "But luckily, it can still catch fish."

"That also tells us something about how men affect nature," he said.

The EAAFP established the Scaly-sided Merganser Task Force in 2010 intending to "restore the Scaly-sided Merganser to favourable conservation status and to remove it from the threatened categories of the IUCN Red List."

"The Scaly-sided Merganser is an important species as this is an endangered species, and its presence is significant as it shows this species may use suitable habitats in HK for wintering. Therefore, it creates more bargaining power for green groups to push for certain areas to remain protected," said local wildlife expert Matthew Kwan Long-hei.

It won’t be long before this single duck flies north to its breeding grounds. For now, the lone female favours the reservoir as her stopover location.

“Knowing its low population, it makes me feel extremely lucky that this lovely duck can be in our Hong Kong,” said Chow.