This is the first of a series Croucher Foundation newsletters to explore and celebrate the biodiversity of Hong Kong. The series will examine how the terrestrial and marine ecology of Hong Kong has changed over time, and will look ahead to future challenges including climate change.
For a relatively small and densely populated region, Hong Kong has remarkable biodiversity. There are 198 species of freshwater fish in Hong Kong (compared with 42 species in UK), and 236 species of butterfly (compared with 59 species in UK).
Hong Kong coastal waters, protected by a recent ban on the use of trawl nets, support similar levels of biodiversity. Over 1,000 species of marine fish are found in Hong Kong coastal waters together with 84 species of hard coral and 67 species of soft coral.
The Hong Kong Country Parks Ordinance enacted in 1976 has restricted urban development to a relatively small proportion of the region. The scientific community is playing a critical role in ongoing efforts to conserve the natural environment in Hong Kong. Over the years, the Foundation has supported many of the scientists who have contributed to our understanding of the local ecosystem. Community organisations including the Conservancy Association, Friends of the Earth, Civic Exchange, and the Hong Kong Bird Watching Society have conducted survey work and advocacy. Smaller community and social media groups promote interest and awareness.
Much remains to be discovered, from the characteristics and lifestyles of numerous species of flora and fauna, to macro questions about the ecological impact of, and mitigations against, urban development, air and water pollution, and climate change.
COMING SOON: Get ready to jump into the deep with Part Two of the Croucher Foundation Ecology Newsletter which will examine our marine environment. Ready for publication in April 2021.
Timeless encounter: view over the mountains, sea, and skyline of Sai Kung and neighbouring islands in Hong Kong’s New Territories. Photo: Gorma Kuma/Shutterstock
What has shaped the extraordinary biodiversity that can be found within the landscapes that comprise the city’s spectacular urban-rural environment, and what do the decades ahead hold?
For a densely packed metropolis, Hong Kong is home to a surprisingly rich biodiversity, with its land area of 1,106 square kilometres encompassing an impressive number of plant and animal species within extensive country parks, 250-plus islands, as well as the more familiar urban areas, mostly located close by mountains, woodlands, and sea.
Hiking in the Hong Kong countryside may bring an encounter with an array of butterflies, dragonflies, lizards that abruptly scuttle for cover, and birds. There are over 200 species of butterflies, 123 types of dragonflies, and 23 kinds of lizards living within its varied landscapes, while the Hong Kong Bird Watching Society lists 559 resident and migratory bird species.
If you are lucky, any one of Hong Kong’s 46 species of land snake may cross your path (there are also six types of sea snake).
Larger mammals are less extensive, given that much of the area’s original broad leaf sub-tropical forests have been stripped away. In addition, those that do survive in forest remnants and re-emerging wooded areas, such as Leopard Cats, Masked Palm Civets, Barking Deer, and Chinese Pangolin, are typically shy, and in the summer, many avoid the daytime heat.
Less shy are the estimated 1,800 wild monkeys – Rhesus Macaque (Macaca mulatta), Long-tailed Macaque (M. fascicularis), and their hybrids – living in 30 social troops in Kam Shan, Lion Rock and Shing Mun country parks in the New Territories. Although originally native to Hong Kong, Rhesus Macaques may have become locally extinct by the Second World War. The macaques today may be descendants of individuals that escaped from captivity, along with macaques released around the Kowloon reservoirs in hopes they would eat strychnos plants that contain a chemical that is toxic to humans but not macaques.
Meanwhile, Wild Boar (Sus scrofa) have survived both deforestation and earlier hunting. Indeed, with predators such as Indochinese Leopards and South China Tigers extirpated (the last in Hong Kong were shot in 1931 and 1942, respectively), and hunting stopped, Wild Boar numbers have risen sharply, with some becoming bold enough to venture into the city.
Hong Kong’s biodiversity is credited to its coastal and delta location on the edge of the tropics, climate, and topography.
Hot, rainy weather from April to September is complemented by cool, dry seasons from October until March, the latter bringing a host of migrant birds to the city, forests, and shorelines. Mountainous, rugged terrain founded on granite and volcanic rock has constrained urban construction and allowed wildlife to survive on the fringes of the city and nearby uplands. Flat alluvial plains in the northwest have supported important wetland habitats, though now heavily encroached on by new towns and village development. More than 2,500 kilometres of natural streams and rivers flowing from the hills nurture upland and lowland ecosystems.
Professor Jim Chi-yung (Croucher Fellowship 1986), Research Chair Professor of Geography and Environmental Science at the Education University of Hong Kong (EduHK), emphasises that Hong Kong has much to celebrate in its biodiversity – and to protect. “We have so much diversity of nature very close to the city. This is a gift for the people of Hong Kong.”
Professor David Dudgeon, Emeritus Chair Professor of Ecology & Biodiversity of the University of Hong Kong, said of this heritage: “What we have is even more remarkable given the sustained and pervasive human impacts on local environments. We have endemic species of frogs, fish, and dragonflies found nowhere else, as well as significant proportions of the global populations of endangered species, such as the Golden Coin Turtle and Black-faced Spoonbill.”
Knowledge on insects and other invertebrates was far from complete. “But what we do know is that Hong Kong seems far richer than one would expect from its small area,” Dudgeon said.
Dr Sung Yik-hei, Assistant Professor at Lingnan University, who researches amphibians and reptiles, expects more to be discovered: “There are still some groups of organisms we know very little about, for example, land snails. We know that there are a number of endemic species, but no one has recorded them.”
Research, he said, had an important role to play: “If we don’t know what species are out there, they could be gone.”
Ice Age Influences
A condensed story of how these natural endowments and the wild side of Hong Kong were formed might start around 18,000 years ago, at the peak of the last ice age. Large expanses of the northern hemisphere were covered by ice sheets. In Asia, permafrost reached as far south as Beijing. With the sea perhaps 120 metres lower than its present level, Hong Kong’s hills were at the northern edge of a coastal plain, extending 120 kilometres to the south.
As the ice sheets melted, the sea rose, eventually reaching Hong Kong, where isolated hills became islands, and flooded valleys were transformed into bays. The climate warmed, becoming more sub-tropical. This, in turn, resulted in changes to local ecosystems, which on land may have mainly been broad-leaved evergreen forests.
While for many plants and animals there were opportunities to spread northwards, species unique to the coastal plain had to move to higher land, or perish.
Clearing the way for human impact
While early humans inhabited the forests and coastal areas, they may have had little impact on ecosystems until around 4,000 years ago, when farmers began clearing land to grow crops and rear livestock.
Within the last 2,000 years, influxes of settlers from the north resulted in increased deforestation, and transformation of landscapes around villages, particularly as lowland areas were used for rice cultivation, and hillside trees felled for different uses, including charcoal production. However, feng shui woods around the villages were nurtured and preserved for the resources and protection from the elements and for water catchments they gave – 116 identified as still standing in a 2002 government-sponsored survey.
In 1841, when Hong Kong Island was ceded to the British, it was infamously dismissed by foreign secretary Lord Palmerston as “a barren rock with nary a house upon it”. Slopes were indeed mostly deforested yet the island was far from barren. The slopes were grassy, while damp gullies and valleys still hosted remnants of woodland where botanists found various species that were new to science, such as the Hong Kong Orchid Tree (Bauhinia × blakeana Dunn), Hong Kong Camellia (Camellia hongkongensis), Hong Kong Dogwood (Dendrobenthamia hongkongensis), and Hong Kong Iris (Iris speculatrix).
These are among about 2,100 species of vascular plants native to Hong Kong that have been recorded and collected by the Hong Kong Herbarium since its founding in 1878 – reflecting the diversity of flora for such a small land area. Another 1,200 exotic species arrived with the different waves of human settlement.
With Hong Kong’s rugged terrain – nearly 80 per cent lies at least 100 metres above sea level – humans have reshaped the land to make way for development, by cutting terraces into hillsides, and through the much greater impact of coastal reclamation. The first land created from the harbour, the Western Praya scheme in the Kennedy Town area, was completed in the 1870s. Since then, reclamation has gradually extended, supporting around 20 per cent of the population, according to the government’s Civil Engineering and Development Department in its history of the city’s changing landscape. Reclamation now accounts for about seven per cent of Hong Kong’s onshore land area.
Safeguarding water and the countryside
Along with reclamation and the limited amount of additional space for nature that it created, reservoirs were built on Hong Kong Island, above Pok Fu Lam (completed in 1863) and at Tai Tam (built between the 1870s and 1912), to support the city. The government planted hundreds of thousands of trees, including pines, gums, Brisbane Box and China Firs, around the reservoirs’ catchment areas. These new woods could act like sponges, storing water during rains and releasing it afterwards, while limiting erosion.
Although there was further deforestation during the Japanese occupation, from late 1941 to 1945, tree planting and forest protection efforts resumed afterwards, likewise prompted by a need to secure water supplies.
Increasingly crowded urban areas contrasted with the wilder mountainous terrain, and led to the protection of that largely uninhabited land as an asset for Hong Kong, culminating in 1976 in the government enacting the Country Parks Ordinance (Cap.208). This involved the establishment of 21 country parks over the following three years, with goals to preserve and improve the countryside, including for nature conservation, outdoor recreation, and education purposes.
Today, there are 24 country parks and 22 special areas, the latter designated mainly for nature conservation, of which 11 are located within the parks. Together, these cover around 40 per cent of Hong Kong’s land area, excluding the 1,500-hectare Mai Po Inner Deep Bay Ramsar site.
Jim of EduHK, together with Dr Wong Fook-yee, former Assistant Director (Country and Marine Parks) at the Agriculture, Fisheries and Conservation Department (AFCD) and now Adjunct Professor in the Department of Geography and Resource Management at Chinese University of Hong Kong, has evaluated the country park system. He describes the percentage of land area as one of the highest proportions of formally protected areas in Asia, and higher than global averages.
The county park system had been successful “mainly due to a strong statutory backup that provides assured legal protection against developments, incompatible intrusions, and land alienation”, Jim said. The protected areas are an important safeguard for Hong Kong’s biodiversity, encompassing around 60 per cent of Hong Kong’s forests, 55 per cent of its shrublands, and 50 per cent of its grasslands, according to the review by Jim and Wong. Ecological surveys they cited indicated that between 96 per cent and 100 per cent of plant and animal species in Hong Kong can be found within them.
Wildlife inhabiting these and other areas has received added protection from the Wild Animals Protection Ordinance (Cap. 170), also enacted in 1976. The ordinance prohibits the hunting or possession of protected wild animals, such as Hong Kong’s bats (more than 20 species), Leopard Cat, Masked Palm Civet, Small Asian Mongoose, Barking Deer, and Burmese Python, among others, but excludes fish and marine invertebrates.
Wong has explained how the parks were carefully designed, with paths constructed to give access to hikers but also to steer them from ecologically sensitive areas, making the parks a sanctuary for flora and fauna as well as humans. Tree planting has continued – at an average of around half a million trees annually in the decade from 2010, AFCD figures indicate.
Around 12 million people visited the country parks in 2020, reflecting their important role in Hong Kong life.
Development vs biodiversity
Dr Gary Ades is Head of Fauna Conservation at Kadoorie Farm and Botanic Garden (KFBG) in the New Territories, initially an experimental farm and now a significant conservation and education centre. Ades credited the country parks with increasing biodiversity. “We have birds expanding their range into Hong Kong from southern China and the region which means our biodiversity is increasing, due to maturation of forests. The country parks and enforcement under the local protection ordinances provide a degree of safety.” However, increased enforcement of that protection was important, he added.
For Dudgeon, the system has its limitations from a biodiversity perspective. “We are fortunate to have such a high proportion of land protected,” he said. “But it is not representative of the habitats in Hong Kong, given that most of the land in country parks is higher than 100 metres above sea level while lowlands are excluded.”
Jim, like Dudgeon, is concerned about the “twilight zone” of fringe development between country parks and main urban areas, where he sees the need for a clearer policy to protect nature.
Lowland sites that have suffered major damage include Sham Chung in the eastern New Territories – which Dudgeon rated the second best freshwater wetland in Hong Kong after Mai Po Marshes, and the place where he discovered the distinctive Hong Kong Paradise Fish (Macropodus hongkongensis). Abandoned paddy fields that had become marshes were bulldozed and drained in the late 1990s. Plans for a private golf course were rejected by the Town Planning Board and the land abandoned. Yet the wetland that once hosted Hong Kong’s largest population of the Hong Kong Paradise Fish – along with other wetland wildlife – was largely destroyed.
Strategies for conservation
However, as global and local awareness has developed, biodiversity and its future has continued to rise up the agenda as a community and policy issue. Alongside the country parks, other infrastructure has been developed for conservation. Adjacent to Deep Bay, WWF-HK manages Mai Po as an important sanctuary not only for birds, but mammals, reptiles, insects, and wetland flora, while KFBG stretches over 148 hectares on the northern slopes of Tai Mo Shan.
KFBG’s public role as a conservation and education centre was officially recognised in a specific ordinance (Cap.1156) in 1995. Since then, it has collaborated with AFCD on conservation and ecosystem restoration, and action plans for specific endangered or at risk species – the Chinese Pangolin, Golden Coin Turtle and Romer’s Tree Frog being three examples. Meanwhile, KFBG Wild Animal Rescue Centre is Hong Kong’s main sanctuary for wild animals that have been injured or rescued from trafficking.
Since the centre opened in 1994, and as of the start of February 2021, it had received 55,613 animals for rescue, treatment and care, and where possible, release back to the wild.
Animal Groups Rescued
|Animal groups received by KFBG since 1994||Numbers|
A “New Nature Conservation Policy” was introduced by government in 2004. This identified 12 Priority Sites for Enhanced Conservation, from Long Valley and Ho Sheung Heung in the northwestern New Territories, to Tai Ho on Lantau Island. Aims included monitoring and mitigation of activities that had an adverse effect on biodiversity; rehabilitating degraded ecosystems and promoting the recovery of threatened species where practicable; and offering incentives for ecologically important sites under private ownership to be allowed limited development in return for their commitment to conservation.
While conservationists question how much has been achieved, the government has pointed to some successes – by 2015 the number of bird species recorded in Long Valley had increased from 221 in 2005 to over 300 in 2015.
In 2016, the government’s commitment to biodiversity was extended further, when the Environment Bureau published the first city-level Hong Kong Biodiversity Strategy and Action Plan. This was prepared as its response to the Convention on Biodiversity (CBD), an international treaty originated from the United Nation’s Earth Summit held in Rio de Janeiro, Brazil, in 1992. China became a party to the CBD in 1993 and extended it to Hong Kong in 2011.
The CBD has aimed to conserve biodiversity, ensure the components of that biodiversity are used sustainably, and promote the fair and equitable sharing of its benefits. The convention provides goals and obligations to guide implementation, albeit with limited global success given the continued depletion of species, from large mammals to birds and insects, and vast tracts of forest areas, in the subsequent decades.
Hong Kong’s Action Plan shares responsibility across relevant bureaux and departments in their planning and oversight, in order to enhance conservation, “mainstream” biodiversity, and improve knowledge and public involvement.
Jim sees it as a step forward. “The AFCD conducted wide consultation of local researchers and green groups to develop a comprehensive plan to enhance our knowledge base, fill in knowledge gaps, and enhance protection of the flora and fauna and their habitats, especially those that are under threat,” he said, adding that it would take time and resources to realise the plan.
Sung also acknowledged some advances. “As an ecologist, it is great to see a lot of work being done. But we are waiting to see the progress and outcomes.” His concern was how this could be balanced with the large-scale development projects that are also planned, such as the Lantau reclamation for Hong Kong’s next major urban area.
“Blue-green” infrastructures creating corridors of water bodies and vegetation in urban areas, and “urban forestry” initiatives for open spaces, are two of the policy directions that have aimed to create an environment where nature can have a better chance of surviving alongside humans.
Some flood prevention works, such as widening of the Upper Lam Tsuen River completed in 2012 that included restoration of the river bed and surrounding plant growth, and protection for its fauna, are presented in the Sustainability Report of the Drainage Services Department (DSD) as pointers to a future strategy that pays greater heed to conservation.
The river is the breeding ground of the Hong Kong Newt (Paramesotriton hongkongensis), classified as near threatened. As reported by DSD civil engineer Keith Tam in an International Water Association article in 2019, the newt was more abundant after the works, having increased from 200 in the pre-construction baseline survey to about 700 in 2017. This was the result of a capture-and-release programme (by KFBG) and conservation measures included in the project that restored other fauna to pre-project levels.
Sung noted that this type of river management was important for amphibians. “When I visited, it was definitely much better. Definitely more organisms can live there compared with traditional concrete conduits,” he said of the Lam Tsuen project, and a similar one at Tung Chung, on Lantau Island.
KFBG’s Ades has worked with the AFCD as a reviewer of species’ assessments for mammals and reptiles of conservation concern. “This has been a useful process, but is not finished yet,” he said, adding that the Biodiversity Strategy and Action Plan had channelled funding into such projects.
While progress has been made, more is needed, according to the ecologists and environmental scientists interviewed for this series.
For Sung, further research on terrestrial and freshwater habitats would be of value, given that little is known about amphibians and reptiles and there could be more new species to discover. Public education on such fauna, and its protection, is also vital.
Jim sees the need to focus on creating more liveable spaces for flora, fauna, and humans within the urban and fringe areas to match the past achievements of the formally protected areas. He champions a way forward involving urban forestry. This seeks to realise ecological, social, and economic benefits, with trees a main component, along with greening of parks, walls, and roofs.
In three to five decades, Hong Kong could be a very green and – as a corollary – healthy city “if we do the right things now”, he said.
For Dudgeon, Hong Kong’s natural heritage and rich biodiversity, as well as the evidence that it is a major transit point or hub for the global wildlife trade, should shape its priorities for the future.
“All of these traits put us in a good position – and mean that we have a responsibility – to contribute to biodiversity conservation, both regionally and globally,” he said.
Hong Kong has one of the last healthy wild populations of the Chinese Pangolin (Manis pentadactyla). Photo : Kadoorie Farm and Botanic Garden
The Hong Kong countryside is a sanctuary for extraordinary animals, some only found in these environs. Below, we spotlight six diverse creatures that are drawing the attention of researchers and conservationists
The Unchartered Life Of The Chinese Pangolin
Little is known about one of Hong Kong’s most elusive, endangered, and endearing species, the Chinese Pangolin (Manis pentadactyla), now the subject of a conservation effort and research involving the Agriculture, Fisheries and Conservation Department (AFCD), Kadoorie Farm and Botanic Garden (KFBG), and other partners, as well as separate research by ecologists at the University of Hong Kong.
Pangolins, also known as scaly anteaters, are a unique group of mammals characterised by their armour of overlapping scales. Powerful limbs and claws for digging, long tapering snouts, and sticky tongues that can stretch to 40 centimetres – sometimes longer than their bodies – have adapted them well for their favourite diet of ants and termites. Without teeth to challenge predators, they curl in a ball when threatened. The Chinese Pangolin, one of eight species of pangolin, grows to around the same size as a corgi dog, a length of around 40 centimetres.
Yet pangolins, which are surprisingly friendly and endearing when encountered in a rescue centre, have the dubious distinction of being billed “the world’s most trafficked mammal”. This is largely due to the demand for their scales in Chinese medicine – despite the scales being made of keratin, the same material as hair and fingernails, with no scientifically proven benefits for human health.
In September 2020, Hong Kong Customs and Excise Department found a tonne of pangolin scales in a consignment of illegal wildlife products being shipped from Indonesia to Mainland China. Thousands of animals would have had to perish to make up such a haul, and over a million are said to have been poached in the past decade.
KFBG’s forensic genetics team is involved in combatting this trade from Southeast Asia and Africa. “Our genetics team was able to discover the region in Africa where White-bellied Pangolins originated by working with African scientists and sharing DNA results,” said Dr Gary Ades, Head of the Fauna Conservation Department, at KFBG.
Meanwhile, Hong Kong’s country parks, with the steep hills that the Chinese Pangolin appears to favour, are an important last sanctuary in the battle against trafficking of the species overall.
“Hong Kong has one of the last healthy wild populations of Chinese Pangolins. This species is extinct over much of its historical range and therefore any programme to protect the species is important globally,” Ades said.
The Chinese Pangolin is listed as critically endangered on the International Union for Conservation and Nature (IUCN) Red List of Threatened Species. KFBG is involved in the government’s species action plan, launched in 2020, through rescue and release work and education to raise awareness of the pangolin and its urgent need for protection. AFCD began surveying pangolin burrows and setting up camera traps over a year ago, which will inform future habitat protection. Any animals being released after rescue may be studied further using radiotelemetry, Ades said.
The KFBG Wild Animal Rescue Centre plays an important role in such conservation by rescuing, treating, and releasing as many pangolins as it can. It is also on the look-out for poachers’ wire or cage traps found in the countryside, which can catch pangolins and many other species.
The risk of poachers targeting the pangolin in Hong Kong is described as real but low in the species action plan. Their major local threat is from feral dogs. Of the 13 pangolins received by the rescue centre since it opened in 1994, five or six were likely to have been attacked by dogs. Ten have been released back to the wild.
“Apart from humans, dogs are the pangolin’s biggest enemy in Hong Kong,” Ades said.
Yet being so elusive means little is known about the Hong Kong pangolin population, its whereabouts, and viability, though the young, injured animals that KFBG has received suggest they are breeding.
Ades is hopeful that AFCD’s conservation project can make a difference. “For me, a key requirement for the protection of local pangolins is to have eyes on the ground studying the animals. We need early warning if poaching becomes a serious issue in Hong Kong and the only way this will happen is if researchers are in the field monitoring burrows and setting up camera traps. Appropriate enforcement work then has to follow.”
Other researchers doing such monitoring include Dr Tim Bonebrake, who leads the Global Change and Tropical Conservation Lab at the University of Hong Kong’s School of Biological Sciences. He has made the Chinese Pangolin the subject of his research, and is sharing information with the AFCD project.
With little information available on the local pangolins, his study, with PhD student Anna Goldman, has involved considerable time and effort simply to figure out where they are, before even considering their habitat requirements. He does not know whether they are so hard to find because they avoid people, or that there are so few of them.
“There’s a lot of evidence, like burrows, we can find in country parks. But we only got our first image after eight months of camera trapping,” he said.
Bonebrake noted that fieldwork in Taiwan has yielded key information on the Chinese Pangolin’s behaviour but elsewhere the species’ range has been poorly studied.
He added that he saw them as “amazing creatures”. “We have some video, including [images of] them digging. While they are armoured, they can move pretty fast.”
However, those combatting the pangolin trade and conserving these mammals need to move fast too if the scaly anteater is to survive.
Freshwater Turtles Threatened In Last Refuge
Losing ground: the city’s environs are a last global refuge for several species of freshwater turtles, including the Beal’s-eyed Turtle (Sacalia bealei). Photo : Sung Yik-hei
Among Hong Kong’s globally significant populations of animals are several species of freshwater turtles for whom the city’s environs have become a last main refuge.
While “turtle” may conjure images of impressively large sea turtles – such as the green turtle, growing to perhaps one metre – Hong Kong’s freshwater turtles are relatively small, with shells no more than a modest 30 centimetres in length. They face severe threats from poaching for the pet trade, food markets, and Chinese medicine, which has devastated their populations elsewhere in the region, and are close to making them extinct in Hong Kong.
Dr Sung Yik-hei, Assistant Professor with the Science Unit, Lingnan University, leads research in Hong Kong on these endangered species, including the Golden Coin (Cuora trifasciata), Big-headed (Platysternon megacephalum), Beal’s-eyed (Sacalia bealei), Chinese Soft-shelled Turtles (Pelodiscus sinensis), and Reeves’ Terrapins (Mauremys reevesii).
By capturing and radio-tracking individuals, Sung has learned about their ecology. He found that they mostly stayed in streams within forested areas, though they might disperse on land during and after heavy rains. One reached a stream at least one kilometre away.
Beal’s-eyed and Golden Coin Turtles may roam further, through forest areas surrounding streams, while Reeves’ Terrapins and Chinese Soft-shelled Turtles prefer flatter, more open areas, for example, around fish ponds.
Most of the turtles, which might live up to 40 to 50 years in the wild, are opportunistic feeders, with a diet including insect larvae, fish, fruit, and seeds – making them valuable seed dispersers.
Along with understanding their ecology, Sung’s marking and radio tracking of turtles has shed insight into poaching. “Last year, a Big-headed Turtle with a microchip we implanted was confiscated when being smuggled to Mainland China. It was recovered, and we released it where it was caught.”
Combatting poaching is a focus of further research that Sung is undertaking, supported by the Ocean Park Conservation Foundation. In this work, he is using infrared cameras to find traps set by hunters, with around 100 located and removed since 2016. He is also working with the government’s Agriculture, Fisheries and Conservation Department (AFCD) on a pilot study to support larger scale patrolling, which he hopes can strengthen enforcement against this illegal trade.
“If poachers visit a site for just two days, half the turtles there may be gone,” said Sung, who despite his efforts is pessimistic about the survival of these species in the wild. “They are very close to being functionally extinct, whereby they can’t perform their ecological functions in the wild, or can’t reproduce,” he said.
The Golden Coin is the most prized by poachers and as a result is now critically endangered. “In the past, it was mainly used for Chinese medicine. People believed it cured cancer.” It is also regarded as a talisman for good fortune, making it sought after in the pet trade and for breeding farms. Individual males have been known to sell for as much as HK$150,000, Sung said.
Meanwhile, AFCD and KFBG have joined forces to conserve Golden Coins in Hong Kong. An assurance colony of rescued animals is being built by KFBG. This includes a breeding programme and eventual plans to release turtles back to their natural habitats.
Dr Gary Ades, Head of the Fauna Conservation Department of KFBG, said: “Our Golden Coin Turtle conservation project is globally the most important project for this species and one that will hopefully prevent the turtle from becoming extinct in the wild.” KFBG urges the public not to buy wild-caught turtles.
Hong Kong’s native fresh water turtles are not to be confused with the turtles adorning ponds in the city’s parks, which are mainly exotic species such as the Red-eared Slider (Trachemys scripta elegans) released by pet owners when they outgrow their tanks. Such releases, particularly when into rivers and reservoirs, pose another threat to the native species, which they are now displacing.
Sung’s interest extends beyond turtles to other reptiles and snakes. A new project, starting in spring 2021, is focused on the status of Bogadek’s Burrowing Lizard (Dibamus bodadeki), a species endemic to three remote islands of Hong Kong: Sunshine Island, Shek Kwu Chau, and Hei Ling Chau.
So far, less than 20 individuals have been found. The first step in the research will be to develop ways to find them – a challenge given that they live largely underground. “If we know more about their distribution, steps can be taken to conserve them,” Sung explained. This was particularly important, given that new reclamation around Lantau Island could affect these islands.
“I hope one day people will value the presence of wild amphibians and reptiles just performing their ecological functions,” he said
Otters Rarely Sighted But Caught On Camera
The elusive Eurasian otter (Lutra lutra): hard to see except via photographs taken with camera traps. Photo : Sharne McMillan
Sharne McMillan, a PhD candidate at the University of Hong Kong’s School of Biological Sciences, has almost completed a study of Eurasian otters (Lutra lutra) in Hong Kong, which she began in 2016. So far, she hasn’t seen one.
However, McMillan has found otter scats, referred to as “spraints”, which she analysed to collect DNA. She has taken photographs with cameras triggered when infrared beams are interrupted, and interviewed local people in the otter’s range, which is nowadays restricted to the Deep Bay area of the northwestern New Territories.
Some people have seen them, such as fish farmers who work at night, she said. “The otters are rare and extremely elusive. They often know we’re there and leave before we can spot them.”
While people traditionally think of otters using underground holts, McMillan has not found any in Hong Kong. Instead, she suspects they may breed and rest on a bed of grass, known as an “otter couch”, as researchers have found in Taiwan. Part of the study involves looking at their habitat preferences, as they evidently favour areas with better vegetation cover and limited disturbance. “They want to feel safe,” McMillan said.
Worldwide, otters living near humans are all too often not safe, due to habitat loss, water pollution, and hunting for their pelts. Some of McMillan’s interviewees told her of otters being hunted in the past, while occasionally the animals were caught in traps set for other creatures such as birds, fish, and shrimps. Overall, interviewees suggested otter numbers had declined over time.
More happily, the interviewees had broadly positive attitudes towards this animal, which is typically considered too rare to significantly predate on fish. A recreational fisherman who supported their protection pointed out that “otherwise they will become extinct and kids [won’t be able to] see them”.
McMillan has viewed tens of thousands of images taken with camera traps. At times, these show nothing, as they might be triggered simply by grass swaying in the wind. But the cameras have also revealed mongooses, civets, snakes, birds – and sometimes, to her delight, an otter.
“Occasionally, I’ve seen images of otters with juveniles, or two otters together,” she said. “That’s very special.”
Along with collecting information, McMillan aims to help inform efforts to protect otters and suggest how they can be surveyed and monitored over the long term. “There’s a lot of interest, and NGOs, researchers, the government, and local people should work together to come up with solutions for conserving the otter,” she said.
Ice-age Relics Winning Battle For Survival
Only in Hong Kong: the 2.5-centimetre Romer’s Tree Frog (Liuixalus romeri), whose known world population live on the islands of Lamma, Lantau, Po Toi, and Chek Lap Kok. Photo : Kadoorie Farm and Botanic Garden
To Dr James Lazell, a former president of the US-based Conservation Agency, Hong Kong is a “biological treasure trove”, which he only discovered by accident when a team of biologists he led was forced to abandon plans for a survey in Mainland China. This was in 1987, and spurred Lazell to make several follow-up visits to search places including Chek Lap Kok, before it was mostly levelled and transformed into Hong Kong International Airport.
Lazell is a herpetologist, and his surveys have yielded 29 species of reptiles and amphibians on Chek Lap Kok – around one-quarter of Hong Kong’s tally. They included Romer’s Tree Frog (Liuixalus romeri), which is endemic to Hong Kong, and named after amateur herpetologist John Romer, who discovered them in a small cave on Lamma Island in 1952.
Romer found more of these tiny frogs, growing to just 2.5 centimetres in length, the next year. But the cave collapsed, and for almost 30 years he searched in vain for them. He died in 1982, believing they had become extinct. But two years later, the frogs were rediscovered on Lamma. Subsequent finds on Lantau, Po Toi, and Chek Lap Kok brought their entire known world distribution to these four Hong Kong islands.
Lazell believes Romer’s Tree Frog and a handful of species that are likewise unique to Hong Kong islands are ice-age relics. They might have been common along a coastal plain that extended along southern China when sea levels were lower during the ice age, but became stranded on hilltops that became islands as the ice sheets melted and the sea inundated the plain.
After the 1990 discovery of the frogs on Chek Lap Kok, herpetologist Dr Michael Lau, chairman of the Hong Kong Wetlands Conservation Association and co-author of Hong Kong Amphibians and Reptiles (1998), scoured the island for more.
He rescued 220 adults before the island was largely levelled to create the new airport. Melbourne Zoo agreed to help with a captive breeding programme, and soon established a healthy population, enabling Lau to release over 1,100 frogs and 1,600 tadpoles at eight sites in Hong Kong.
Today, five of those eight translocated populations have survived, with at least three spreading up to two kilometres, according to Lau, who teaches on the Conservation Biology and Management Master’s programme at the University of Hong Kong.
Romer’s Tree Frogs are monitored and surveyed by the Agriculture, Fisheries and Conservation Department, among others, which has provided up-to-date information on the distribution of this unique species. However, a full population estimate has yet to be done. The largest population is at Ngong Ping, Lantau, and as a result this has been designated a Site of Special Scientific Interest since 1999.
The Tung Chung New Town extension may impinge on some of the habitats but Lau said that the frogs affected would be translocated again to suitable sites nearby. “Since it is protected with a species action plan, the habitat requirement and ecology is well studied, and will be flagged in EIAs [environmental impact assessments] and planning studies, should it be affected by development,” he said.
In addition, existing populations on Lantau and Lamma have expanded since the early 1990s as the forests there mature. “I think the future of this species is quite secure,” Lau said.
Meanwhile, new species of amphibians and reptiles in Hong Kong continue to be found, with recent discoveries including Lau’s Leaf Litter Frog (Leptolalax laui), which is named after Lau.
Hong Kong's Very Own Paradise Fish
The Hong Kong Paradise Fish (Macropodus hongkongensis), a species new to science, was discovered in the 1990s. Photo : Agriculture, Fisheries and Conservation Department, HKSAR Government
Among other vertebrates first found in Hong Kong and new to science is a type of paradise fish. Researchers including David Dudgeon, Emeritus Chair Professor in Ecology and Biodiversity at the University of Hong Kong, discovered this fish in 1996. It was subsequently identified from its morphology and named the Hong Kong Paradise Fish (Macropodus hongkongensis) by researchers in Germany, while recent genetic work has confirmed that it is distinct from other paradise fishes in Southeast Asia.
Distinguishing features of the Hong Kong Paradise Fish, which has long elegant fins, and red pelvic fins, include black spots on its head and body as well as a white first ray on the pelvic fin. Like other paradise fishes, the male builds and guards a floating bubble nest, in which the eggs and developing young are tended. The female takes no part in parental care.
The Hong Kong Paradise Fish was initially believed to be endemic to Hong Kong, though soon after was found to be present in eastern Guangdong and Fujian. In Hong Kong, it lives in slow-moving streams and wetlands in Sai Kung, Tai Po, and the northern New Territories.
In 2019, a team of biologists from Nanjing Forestry University investigated further, completing the first mitogenome sequence of the Hong Kong-named fish. This determined its uniqueness, and that its closest relative was the Red-back Paradise Fish (Macropodus erythropterus), endemic to Vietnam and sequenced in 2016, rather than the more common Chinese Paradise Fish (Macropodus opercularis) found in Hong Kong and elsewhere in China.
The Hong Kong Paradise Fish is one of 185 freshwater fish recorded in Hong Kong and listed among 21 of “conservation concern” by the Agriculture, Fisheries, and Conservation Department, which has recognised threats to such biodiversity from habitat loss and degradation, climate change, over-harvesting, pollution, and the presence of exotic species – factors that have caused a rapid global decline of freshwater fish populations.
Dudgeon would also like the Hong Kong Paradise Fish included on the International Union for Conservation and Nature (IUCN) Red List of Threatened Species, as has been the case with the Hong Kong Newt (Paramesotriton hongkongensis). “There is a real risk of over-exploitation, and ‘conservation concern’ does not protect animals from collection if they are outside Hong Kong’s country parks,” he said.
Meanwhile, this particular fish has one special status, as the only freshwater fish species named after Hong Kong.
Ants Can Be Smart – And Fiery
Weaver Ants (Oecophylla smaragdina), a species native to Hong Kong. Photo : Francois Brassard
While endangered, appealing vertebrates often grab the limelight, there is much more to Hong Kong’s biodiversity as a whole. Ant species alone extend to several hundred.
Dr Benoit Guénard, of the University of Hong Kong’s School of Biological Sciences, studies insects, especially ants. To Guénard, ants are important for their interactions with other groups of organisms, helping seed dispersal, aerating and enriching soil, and playing their role in the nutrient cycle, among others.
“They are huge in terms of predation – removing many herbivorous insects, so we have forests,” he said. He is particularly intrigued by their behaviour as social insects and how this contributes to their success.
Guénard is now continuing research on Hong Kong ants, one of the insect groups with relatively strong data to build on. During his career he has described 27 insects such as ants, flies, and wasps that were new to science, the most recent being four new ant species from Hong Kong and Macau, of the genus Polyrhachis, along with seven of that genus that were newly recorded in this area, published in Asian Myrmecology in February 2021.
The seven-millimetre-long Paratopula bauhinia, named in the vernacular as the Golden Tree Ant, was the first species Guénard described in Hong Kong, in an article also published in Asian Myrmecology in 2016. The discovery proved especially notable as the ant is the only member of its genus yet known in Hong Kong.
As its name suggests, this is a forest ant, resting on trees during the day and, as evening approaches, descending to forage in lower vegetation during the night. Guénard and researcher Ying Luo found such ants just a few hundred metres from the university and, to date, they are unique to Hong Kong Island.
Since then, he has described eight more ant species, three species of flies and two species of wasps from Hong Kong. He explained that a newly described species indicates that it is considered new for science.
“First a species has to be described by taxonomists, not only to have a name, but most importantly to have a description that will distinguish it from all other species. Once it has a name, a species can be recorded from other regions, so the knowledge on the species distribution improves.
“Both taxonomic descriptions (‘naming’) and recording (‘knowing the distribution of a species’) are important steps in order to study them, and eventually protect them,” he said.
“Finding new species is not so unusual when you’re an entomologist,” he said. “But it’s always exciting, describing something nobody has found.”
Many more are likely to be discovered. “We are still working on a final list of the ants of Hong Kong, and still frequently discover new records and new species. It seems reasonable to say that between 300 to 400 species of ants can be found in Hong Kong,” he said. Ant species known globally extend to more than 15,700, a number expected to increase considerably in the coming years.
Not all ants are welcome. Several are “invasives” – exotic species introduced by humans and with some negative impacts on biodiversity, and even people. “Hong Kong has one of the highest densities of invasive species in the world, only exceeded by Hawaii and Florida,” Guénard said.
“At ecosystem level, there’s something like an equilibrium between predators and prey that may have evolved over millions of years. But when species from outside arrive, they are playing a different game,” he explained.
The Red Imported Fire Ant (Solenopsis invicta), which is native to South America and named for its intensely painful sting, is especially prominent among Hong Kong’s invasive ants. Guénard is studying fire ants here, and has learned that some farmers are so deterred by the stings that they give up farming part of their land.
Native ants, by contrast, play an important role in local ecosystems. For instance, Weaver Ants (Oecophylla smaragdina) defend trees against herbivores. They make nests by sewing leaves together, forming brown, ball-like structures that are easily spotted in branches.
“If you look in a nest, you find a community of insects within,” Guénard said. “There are species that mimic ants – such as spiders that prey on them, and juvenile stick insects that avoid predation by living amongst the ants. Others are kept by ants for food. With invasives, you lose all of this interdependence.”
Chinese Banyan trees (Ficus microcarpa) have taken root on stone walls in various areas of Hong Kong and are among 1.7 million trees of different species being managed in the city. Photo : Creative Commons/Wikimedia
Venerable Chinese Banyans are among the thousands of trees that squeeze within Hong Kong’s high-rises. What does the future hold for them and the city’s greening endeavours?
Nature literally clings to life in Hong Kong’s dense urban areas in the form of the city’s vast “champion trees” – some up to 400 years old – and the fauna they host.
These are the Chinese Banyans (Ficus microcarpa) that drop and spread their roots along the stone walls found on Battery Path in Central, in Kennedy Town’s Forbes Street, and on other roads on Hong Kong Island, that have stood broad and tall in Kowloon Park since the early Qing Dynasty, and, as some still believe, act as a safe haven for the gods among Hong Kong’s last temple trees and feng shui woods.
They cool the city’s streets and parks, and support a vast array of wildlife, from Masked Palm Civets (Paguma larvata) and Pallas’s Squirrels (Callosciurus erythraeus) to bats such as the Short-nosed Fruit Bat (Cynopterus sphinx) and birds such as noisy Mynas (Acridotheres tristis).
Today there are about 300 ancient banyans in city areas, according to Professor Jim Chi-yung (Croucher Fellowship 1986). Jim is Research Chair Professor of Geography and Environmental Science at the Education University of Hong Kong, and a leading international researcher, educator, and advocate for understanding, conserving, creating, and refining nature in cities.
“They are a part of our history. This is our communal memory,” he said, adding that Hong Kong is unique in the way so many have managed to take root in the tiniest crevices, and grow to urban giants.
“Many are growing on stone walls, having seeded spontaneously, with the help of the birds and bats that enjoy their fruit,” he said. “Nowhere in the world has so many.”
As in numerous cities around the world, Hong Kong’s urban planners and researchers aspire to preserve or create a green environment in parks, within new developments, and roadside areas. But trees in the local urban landscape face particular challenges as their roots and crowns compete for space needed for their health. Typhoons, heavy rains in summer, and drought in winter add to the stresses.
2010/11 to 2019/20
Urban areas: 544,300
Rural areas: 5,718,500
Source: Development Bureau
Jim has led extensive survey work that has taken stock of Hong Kong’s arboreal assets in urban and rural areas, how trees are faring, and how they can best grow in stressful city conditions. He is the most cited scholar in the world in the field of urban greening, according to ISI Web of Science.
Following surveys in 1994, 2000, and 2008, he published a study in 2012 enumerating 19,154 trees in and around Hong Kong’s urban areas, including 149 species in 45 botanical families. As a result of the surveys, the government formed and now keeps a register of around 460 “Old and Valuable Trees” on unleased government land in urban areas –“old” being more than 100 years old, and “valuable” being trees that are large, of “outstanding form”, rare, or of cultural or historic significance. However, as a 2019 Legislative Council brief explains, there is no legislative or regulatory protection for trees on the register.
On Hong Kong Island and in Kowloon, 138 stonewall trees, including 98 Chinese Banyans, 24 White Fig (Ficus Virens) and seven Japanese Superb Fig (Ficus subpisocarpa), are managed by the Architectural Services Department (ASD). According to ASD, initiatives helping these historic trees to thrive have ranged from shifting the proposed footprint of the Kennedy Town MTR Station to minimise the impact on the stonewall trees in Forbes Street, to creating planters for their roots, guiding and trimming aerial roots, and using sensors to monitor their health.
However, unlike many cities, Hong Kong’s roads and pavements are narrow, with buildings occupying the bulk of the land space. “Because it is ultra-compact, we have very little space for greening,” Jim explained.
“Conditions for tree growth are pretty poor,” he added.
Just how poor was evident recently, when at least 60,000 were destroyed in August 2018 when Typhoon Mangkhut ripped through the city, according to official records. Jim estimates the number to be closer to 100,000. These included some of the large banyans and cotton trees, along with many non-native Acacias (Acacia confusa).
His review of the damage after the 2018 typhoon showed that many of the fallen trees had lacked adequate root space and soil to withstand a strong typhoon, having been planted in small tree pits or with roots damaged by construction activity.
Within two years, many of the empty pits were refilled with new trees, but his recent surveys have indicated that many sites were not improved before replanting, Jim said.
Entrenched practices needed to change, he noted. “We must improve the site conditions, soil quality, method of planting, and choose the right species,” he said, with the species depending on the space and soil conditions, factors that should be incorporated into landscape design.
The Development Bureau, which has a coordinating role for tree management, noted in a written response the importance of “right tree, right place”, with wider use of different species encouraged to increase their resilience to pests and diseases, and the aim to provide adequate space for healthy tree growth.
It stated: “We promote a holistic greening approach, embracing adequate space allocation for new planting, proper selection of planting species as well as quality landscape design.”
Proactive management is needed for the estimated 1.7 million trees in urban areas, with policy evolving over the years from tree planting, management and maintenance to the more holistic concept of urban forestry that recognises the multiple disciplines and benefits involved in a rich urban ecology.
That ambition is complicated by the fact that this task is spread across nine core government departments. The Leisure and Cultural Services Department, with an estimated 598,000 trees located along urban roadsides and in venues such as public parks; and the Highways Department, with 590,000 trees beside expressways and roadside manmade slopes and walls, have the largest commitments.
In 2017, the Development Bureau set up the Urban Forestry Advisory Panel so policy could be better informed by science and applied research by drawing on the expertise of academics and professionals from fields such as urban forestry, plant science, engineering, and landscape architecture.
A major on-going task involves the removal of thousands of senescent trees, and replanting, as undertaken by the Highways Department in pilot areas such as Wong Tai Sin and Shatin and study sites along Tai Tong Shan Road.
In the Highways Department programme, its landscape architects have worked with environmental scientists, tree management researchers, and ecologists at Chinese University of Hong Kong and Hong Kong Baptist University College of International Education to replace Acacia trees. Acacias are an exotic, fast-growing species of limited ecological value planted extensively in the 1950s along highways and now approaching the end of their lives.
Smaller native and localised trees, shrubs, and ground cover that can enhance biodiversity and environmental performance are being used to replace them, such as Celtis, Bauhinia, and Ilex species among the trees, Rhododendron, Ixora, and Hibiscus among the shrubs, and Tuberous Sword Fern for ground cover – now attracting a wider range of birds and butterflies, according to the surveys being conducted.
Dr Amos Tai (Croucher Fellowship 2012) is Associate Professor in the Earth System Science Programme and Graduate Division of Earth and Atmospheric Sciences at the Chinese University of Hong Kong and one of the principal investigators on the Tai Tong Shan Road study. “This is an important project to reveal the existing problems of Acacia plantations,” he explained.
These include fungal diseases, reduced ecosystem services, such as carbon and pollutant uptake, ageing trees in poor health that have a high likelihood of falling during strong storms, and poor facilitation of biodiversity. “We found that replacing mature, failing exotic Acacia with native, actively growing young trees and shrubs can have multiple benefits that counter these problems,” Tai said.
His particular role involved measuring the leaf density and photosynthetic capacity (i.e. primary productivity) of the mature Acacia as well as the replanted and wild native trees at the study sites. Data was fed into a computer model to estimate the ecosystem services in terms of carbon and pollutant uptake provided by the different trees. “We found that Acacia provides less of all those services than the replanted or [wild] native trees,” he said.
The initiative, he added, was now a work in progress. The success would be seen in the decades ahead. “But theoretically, the programme has preliminary great potential,” he said.
Dr Alvin Tang, Hong Kong Baptist University College of International Education Tree Management Programme Course Co-ordinator, who was responsible for the tree health assessment on this project, explained: “After each event [such as a typhoon], the government tries to promote a better practice and guidelines for planting. However, there are always gaps between advocating and implementing because there are no strict rules and regulations.”
He is contributing to better practice through his involvement in the development of Arboriculture and Horticulture within the Hong Kong Qualifications Framework, and in training practitioners for a professional diploma in tree management – helping to address the government’s concern that Hong Kong lacks capacity in terms of the supply of qualified personnel to inspect and manage so many trees, whether on public or private land.
Another initiative looking to the future is the HK$32 million Jockey Club Smart City Tree Management Project, which has brought together science and the community to promote better management, care, and knowledge of trees.
The three-year scheme, ending in 2021 and funded by the Hong Kong Jockey Club Charities Trust, has involved research collaboration with Hong Kong Polytechnic University, University of Hong Kong, and Hong Kong University of Science and Technology, as well as participation by the Development Bureau and Friends of the Earth (HK).
The universities have developed smart-city sensing technology to monitor tree health, for example, how they respond to wind force and root movement so that arborists can follow up to treat a tree before it succumbs to another big typhoon. Friends of the Earth (HK) has been encouraging its supporters to become tree monitors.
Feng shui woods and their traditional benefits
While science and education can help inform practice today, Hong Kong can also draw on the special place of the tree in Chinese culture and village life.
Traditionally, trees such as Chinese Banyan (Ficus microcarpa), Incense (Aquilaria sinensis), and Camphor (Cinnamomum camphora) were planted in crescents of woodland around a village to create a microclimate for cooling in summer and protection from cold winds in winter, to prevent soil erosion, and ensure soil and water conservation. They were also important for their supplies of firewood, fruit, nuts, and medicines. Popular fruits such as longan, lychee, guava, and papaya were planted on their fringes.
These were feng shui woods, of which more than 116 have been surveyed by the Agriculture, Fisheries and Conservation Department’s Plant Working Group. Examples listed by the Hong Kong Herbarium include Lai Chi Wo on the northeastern border and Lai Chi Chong in Sai Kung, and even on the fringes of the city on Hong Kong Island, in Aberdeen.
Jim said: “They brought tremendous benefits to the village, for generation after generation. In the old days, scholars introduced the idea of superstition to convince illiterate farmers not to damage the trees. It became an ill omen to harm a tree. But we have been severed from past customs, and respect for nature.” He sees public education as vital to rekindling that care for trees, and is developing an app for that purpose.
Tai is especially interested in how trees can help cool city streets by providing shade, and through transpiration, though there is a catch. “Alongside roads, trees can emit VOCs [volatile organic compounds], and these can react under sunlight with nitrogen oxides from cars and other vehicles to create ozone,” he said.
“So we need care with what kind of trees are planted. They should not emit too many VOCs.” He cited Bamboo (Bambusa multiplex), Weeping Willow (Salix babylonica), Fishtail Palm (Caryota mitis), and the Chinese White Poplar (Populus tomentosa) among the trees and plants commonly found in Hong Kong roadside areas that are susceptible to excess VOC emissions.
Another ecologist, and member of the Urban Forestry Advisory Panel, who has shared advice on what to plant is Dr Billy Hau, Programme Director of the MSc in Environmental Management at the University of Hong Kong, and founder of the Native Tree Nursery at Kadoorie Farm and Botanic Garden that promotes the use of native species in forest restoration.
His 2011 review on biodiversity for a Development Bureau plan on street tree management identified 191 plant species, ranging from herbs to shrubs and trees, that offer a range of benefits to urban birds, mammals, and butterflies. “Future landscape design in Hong Kong with the aims of promoting biodiversity conservation could take reference to this list in selecting plant species,” he suggested. About half of these species are native, recommended for attracting more birds and other wildlife.
He sees that Hong Kong has made progress in making room for nature in park areas and other open spaces. “If you look at the planting [at] the Central Government Offices and Lung Wo Road – using planter beds rather than tree pits – it is a lot better than the old designs.”
Ecologists and environmentalists also advocate practice in tree and park management that is not only beautiful to the human eye, but goes further in incorporating the needs of other creatures to achieve the “living in harmony with nature” as envisaged in the Convention on Biological Diversity’s Strategic Plan 2011-2021.
Jim said: “The worldwide enlightened trend is to adopt a naturalistic approach to design and manage urban parks. It is time that our parks are nurtured to fulfil the shared expectations of both people and our wildlife companions.
“After all, parks were initiated in modern times as emulations of nature rather than human domination over nature.”
Walls and roofs that nurture nature
The green roof of the Central-Wanchai bypass tunnel: building science researcher Dr Caroline Chan sees vertical greening is of paramount importance as Hong Kong’s population and urban areas continue to grow. Photo : kylauf/Shutterstock
One way to expand space for nature in such a dense, high-rise city as Hong Kong is to extend the greenery upwards in the form of vertical green walls, and roof gardens and woodlands.
The Hong Kong government sets minimum requirements for green space around buildings, and encourages sky gardens in the Development Bureau’s Sustainable Building Design Guidelines. But in vertical greening, the city is lagging behind Singapore, according to researchers.
However, there are examples of green-clad buildings established long enough to prove they not only improve the energy efficiency of the building, but have also become established homes for birds and insects.
Professor Jim Chi-yung, of the Education University of Hong Kong, and known as the father of the city’s green roof movement, is delighted that the green wall wrapping and rooftop woodland that he designed and completed for China Light and Power (CLP)’s substation at Chui Ling Road in Tseung Kwan O in 2013 is continuing to thrive today.
Rather than using planters to green the 500-square-metre façade, Jim employed “nature’s climbers”, such as Chinese Wisteria, Japanese Honeysuckle, and Firecracker Vine. For the Sky Woodland on the 520-square-metre roof areas, Hong Kong Camellia, Incense Trees, and Scarlet Sterculia were among 80 trees from 32 native species planted. This is now home to nesting birds, bees, butterflies, and other insects.
Jim is continuing to explore the area, leading research to investigate the optimal soil conditions for green walls and roofs, and their cooling and energy-saving benefits. A 2020 study showed that a woodland canopy intercepted about 90 per cent of incoming solar radiation, and on sunny days reduced highest mean surface temperatures by 2.77 degrees Celsius, and the air temperature by 2.27 degrees Celsius.
Meanwhile, he has indicated that safety elements – such as loading limits and drainage – also needed to be informed by science and need not limit the ambitions for more green buildings.
“Green roofs are important islands of nature in the city,” he said.
Indeed, flocks of sparrows and Black-collared Starlings can now be seen foraging in the grass of one of the largest of the city’s green roofs, above the Central-Wan Chai bypass tunnel portal, commissioned by the Highways Department. The tunnel opened to traffic in 2019.
Other Hong Kong researchers have utilised their expertise in architectural and building science to inform greater use of vertical greening, including on skyscrapers.
Research by Dr Caroline Chan, Lecturer in Building Science and Technology at City University of Hong Kong, described vertical greening as of paramount importance as Hong Kong’s population and urban areas continue to expand.
She has explored why there has been little application of vertical green walls, with Hong Kong trailing Singapore in terms of high-rises with self-sustaining vegetation for cladding. This is despite widespread local and international interest in the benefits of such walls, for reduced energy consumption, mitigating against air pollution, and increasing biodiversity in the city.
Vertical greening has been used on government and utility buildings, and retail levels of some recent developments, such as the living wall for the K11 Musea retail and cultural complex in Tsim Sha Tsui, but does not match Singapore in reaching to the higher levels of city skyscrapers.
Chan’s survey of architects, published in 2018, indicated the mix of incentives and guidelines that could help developers green their buildings upwards to overcome the higher initial costs and price of maintaining a green façade.
“There are improvements in Hong Kong,” she said. “More greening has been done by the government and private sector. New developments are usually larger in scale, which make them more flexible to incorporate green designs in the planning stage.”
Additional education was needed to promote sustainable design knowledge among young professionals, with this area included in university courses, research, and community activities such as design competitions and exhibitions, Chan said.
While Chan cites improving biodiversity by creating habitats for birds, insects and microorganisms as a benefit of greening, “attracting pests and unwanted animals” was, ironically, a concern among the surveyed architects, as were technical issues such as implications for structural load capacity and damage to the building.
Hong Kong buildings could go greener if there was “more research related to the technical issues such as the suitable species for growth in Hong Kong in view of the climate change in recent years, design details for cost-effective greening options, especially for cutting costs in the maintenance period, and technical guidelines for designers and building owners”, she said.
Meanwhile, fieldwork and modelling by a research team at Chinese University of Hong Kong’s School of Architecture and Institute of Future Cities, published in 2017, found that such efforts would be worthwhile. Greening 30 to 50 per cent of high-rise facades could make for a more comfortable city by reducing daytime and night-time temperatures by one degree Celsius. The team advocated that greening at ground level, vertical facades, and roofs should be included in the urban planning process.
But equally important, such greening brings quick benefits for nature too. Jim said of the CLP sub-station project: “When we started planting trees, they had not even settled in the soil when the birds and butterflies began to come.”
Surviving amid the urban jungle
Red-whiskered Bulbul ( Pycnonotus jocosus ). Photo : Wei Shyy
Geography and climate account for more than 550 species of birds that live or vacation in Hong Kong and its environs, with an impressive mix prospering in the midst of the metropolis.
If you stroll through one of Hong Kong’s urban parks – Kowloon Park, King’s Park, Victoria Park, or Hong Kong Park, for example – you are likely to find several of the city’s more familiar birds. Chinese and Red-whiskered Bulbuls can be seen on prominent perches in shrubs and trees, easily noted thanks to their effervescent calls and the latter’s distinctive black crest, Oriental Magpie-Robins in full and varied song may be spotted on fences, while Black-Collared Starlings might be strutting about on lawns.
Masked Laughingthrushes could be foraging quietly in shrubs, with Tailorbirds also preferring low cover. There may also be a fleeting glimpse of a tiny Fork-tailed Sunbird – the male flashy red, turquoise and white, the female an elegant green – hovering for nectar around red flowers, with Hibiscus and Mexican Fire Spike being two favourites.
Compared with cities such as Beijing and Shanghai, Hong Kong’s parks and surrounding areas also attract more elusive forest birds, according to Dr Caroline Dingle, who leads the Tropical and Urban Evolutionary Ecology research group at the University of Hong Kong’s Faculty of Science and is conducting research on how birds have adapted to urban life.
These include Scarlet Minivets that have recently extended their range to locations such as Hong Kong Park, where flashes of the yellow female and scarlet male can be seen. Turquoise Verditer Flycatchers can also be spotted flying from tree to tree in winter months.
Dingle explained that this diversity in avifauna is due to the city’s remarkably compact urban areas, which means that none of its urban parks are far from the forested hills of Hong Kong Island and the New Territories.
Of the 559 different species of birds recorded in Hong Kong, just over 100 species have been seen in urban areas. Of these, close to half are resident.
Most of Hong Kong’s birds are seasonal (spending the winter), passage birds, or vagrants straying beyond their normal territories, according to Yu Yat-tung, Research Manager of the Hong Kong Bird Watching Society (HKBWS). Only around 20 per cent of all bird species recorded are residents, taking into account the many shorebirds that visit the wetland areas.
Hong Kong attracts these visitors because of its location between temperate and tropical areas in the middle of the East Asian-Australasian Flyway, a climate that caters for all birds at different times of the year, and the wide range of habitats – woodlands, grasslands, farmland, and the marine environment within short distances of the urban areas and their parks, he said.
Access to such a range of habitats has made it an ideal stopover for birds travelling from the Northern Hemisphere to the Southern Hemisphere, and vice versa. These include forest birds escaping the colder winters to the north, as well as the many more species of shorebirds heading to Deep Bay and the surrounding wetlands.
The range of birds to be found in pockets of the city and its fringes can be illustrated by three better-known families of forest birds: 40 species of flycatcher and other birds of the Muscicapidae family; 28 species of leaf warbler (Phylloscopidae family); and 10 species of thrush (Turdidae family), mostly passage migrants.
How urban parks and other open spaces in the city are managed is important to biodiversity. But it is a contentious issue when the types of plants chosen, concreting, regular cleaning, and use of insecticides to combat mosquitoes can make these areas less welcoming for wildlife.
After Kowloon Park was redeveloped in the late 1980s, its surviving banyans plus extensive shrubberies helped make it a hotspot for migratory birds. The HKBWS advised park management to include wilder vegetation in the conservation corner that was established. Yet the society’s records show bird sightings have since declined, as the park has become more managed.
Yu said: “HKBWS has suggested that they reduce the frequency of cleaning and vegetation management.”
However, an ornamental bird lake, with its ready supply of fish and surrounding tree canopies, has attracted a community of Black-crowned Night Herons, an example of how nature can be accommodated in a city.
The HKU urban ecologists have conducted research on how the types of habitats and shrubs found in parks may affect birds. Surprisingly, the study conducted by MPhil student Chan Wai-shan found that the diversity of habitats did not affect the number of species or abundance of birds. “In a small park with many different habitat types, the size of each habitat might become too small to support any specialists,” Dingle explained.
She suggested that landscape architects could work more closely with ecologists to ensure that the shrubs and trees chosen, and how they are managed, are good for birds and other fauna, as well as humans.
Meanwhile, Dingle is investigating how the more common resident species, such as bulbuls, doves, and sparrows cope with city life, in particular the noise.
“We find that most species of birds increase the frequency of their vocalisations in the presence of urban noise,” she said. “Urban noise tends to be low frequency, so by shifting their songs upwards, birds may be able to avoid their signals being masked by the traffic noise.
“We have also shown that these shifts lead to changes in response behaviour. When a bird in a city hears songs recorded in noisy and quiet areas, it responds much more strongly to the song that has been adjusted to noise.”
This is important as those unable to adjust may show reduced fitness. “They may be less likely to attract a mate or defend a good territory, so may not have as many offspring.”
However, Hong Kong’s advantage for its birds is that they do not have to go far to escape from the urban jungle.
Endangered Cockatoos Find Free-flying Refuge
Living it up: 150 to 200 Yellow-crested Cockatoos (Cacatua sulphurea) now reside in Hong Kong, one-tenth of the world population in the wild. Photo : John Holmes
One of the joys around and above the skyscrapers of Hong Kong Island is the sight of the Yellow-crested Cockatoo, not in a cage but flying wild.
In fact, this bird is not a Hong Konger at all, but an introduced species living far from its original home of Indonesia. However, it has become a well-established city resident, and given it is rated as a critically endangered species by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, its presence in Hong Kong is now important for its survival.
Free-flying cockatoos, likely to have escaped from captivity, were first recorded in Hong Kong in the late 1950s, according to the University of Hong Kong’s Dr Caroline Dingle, whose team studies this species in the city, among others. Cockatoos found fruits and nuts, and even nectar from Cotton Trees to their liking, along with holes in trees where they could breed and establish a population.
Today, there are around 150 to 200 cockatoos living wild on Hong Kong Island – almost one-tenth of the world population in the wild.
“ Not many cities are a safe haven for a critically endangered species ”
- Dr Caroline Dingle
“Although Hong Kong is not the native habitat for this species, the Hong Kong population is now likely one of the biggest populations of the cockatoo, and is relatively safe from trapping,” Dingle said. “One of our goals is to monitor their breeding success to determine whether this population is likely to persist.” There was no evidence that the introduced species was having any negative impact on the local ecology, she added.
The study could also help determine whether the Hong Kong population is healthy enough to allow some to be captured, and released in the species’ native Indonesia, where demand for the pet trade has devastated its population, particularly in the east of the country.
Meanwhile, Dingle’s focus is on ensuring they survive here. “Not many cities are a safe haven for a critically endangered species,” she said. “They are an incredible asset for Hong Kong. You look out of the window, and they are just outside.”
Ho Man Tin Oasis Draws Migratory Birds
Passing through: the rarely seen Fairy Pitta (Pitta nympha) appears in the residential district in spring or autumn. Photo : Michelle & Peter Wong
Many birds heading into Hong Kong on a stopover or winter basis have found a surprising haven in the heart of the city.
Ho Man Tin, a mainly residential area in Kowloon, has become a popular birdwatching destination to catch sight of these migrants, thanks to a combination of a favourable woodland habitat bordering its reservoir and pioneering observations by citizen scientist John Chow.
Chow works as a school science laboratory technician in the Ho Man Tin district. In 2012, a friend introduced him to birdwatching, a turning point in his life. He had taken students on outings to learn about astronomy, but found birds living so close to humans could be a greater inspiration for them.
He began learning more, including taking a course with the Hong Kong Bird Watching Society (HKBWS).
To Chow, even well-known birds can be intriguing, such as the mysterious meanings of the calls of the Cinereous Tit. He also began finding migrants that were uncommon or extremely rare in Hong Kong, including Narcissus Flycatchers with black upperparts and brilliant orange-yellow underparts.
News of his sightings spread among the birdwatching and bird photography community, and Ho Man Tin soon rose up the ranks of Hong Kong birdwatching sites.
Chow voluntarily contributes to knowledge of Hong Kong’s birdlife through fieldwork and submitting observations to the HKBWS, along with taking students on outings to inform and encourage them to learn about the natural world.
“There are many special records from Ho Man Tin,” he said. “The first spring Black-headed Bunting; the first Tiger Shrike with its breeding plumage; the latest spring Yellow-browed Warbler.”
Some birds, such as Tiger Shrikes, rest up in Ho Man Tin more than other areas of Hong Kong, Chow said. Others, such as the Brown-chested Jungle Flycatcher (another Hong Kong rarity, which Birdlife International ranks vulnerable to extinction), always visit the same tree in the area at the same time of year.
From 10 to 50 birdwatchers may visit Ho Man Tin each day during the peak autumn period. Even more might gather when there is a notable rarity, such as when a Fairy Pitta – a relative of thrushes with plumage that would make a kingfisher proud – stops over during a spring or autumn migration.
However, Chow added that his records show that fewer birds are now wintering in the area, which he believes may be due to climate disruption and loss of habitats beyond Hong Kong.
As such, while Hong Kong may stand out in having so many birds in and close to the city. these creatures are also a reminder that such biodiversity requires not only local care and conservation, but is interconnected to the regional and global challenges facing nature.
Forest and grassland of global significance for flyers
Individual characteristics: a 2010 study found the Chinese Grassbird (Graminicola striatus), pictured here, to be a separate species not a sub-species of the Rufous-rumped Grassbird (Graminicola bengalensis). Photo: Tim Boucher
Global conservation organisation Birdlife International has established a system of Important Bird Areas (IBAs), places of international significance for the conservation of birds and other biodiversity. To date, there are over 13,000 IBAs, two of which are in Hong Kong.
One covers Deep Bay in the northwest New Territories, and the second encompasses the conservation area of the forests and grassy slopes of Tai Po Kau, Shing Mun, and Tai Mo Shan in the central New Territories.
The forests in this second area were mainly planted after 1946. While the reforestation efforts included a handful of non-native tree species, such as Brisbane Box, there was also some emphasis on native tree species, particularly within the Tai Po Kau Nature Reserve, on the lower, eastern slopes of the Tai Mo Shan massif into which the IBA extends.
As the secondary forests developed, they began attracting more wildlife, including mammals such as Barking Deer, Civet Cats, East Asian Porcupines, and even the Chinese Pangolin, according to the government’s Agriculture, Fisheries and Conservation Department (AFCD), which manages the area.
Among birds, some were winter visitors from Mainland China that began settling to breed, such as Chestnut Bulbuls and Scarlet and Grey-chinned Minivets. Over time, a bird community became established, which may be similar to the birdlife of the original Hong Kong forests, where large numbers of butterflies can also be seen in spring and autumn.
Regarded as a representative site of the wider South China Mountains stretching from Yunnan Province to Guangdong, the New Territories IBA-designated area is now important for scientific research and long-term monitoring for the region.
Since the area joined the IBA system in 2004, monitoring has been on-going. This is carried out by the AFCD’s Bird Working Group, which conducts surveys of birds to inform AFCD avifauna conservation efforts as part of the management of Hong Kong’s protected areas, and birdwatchers reporting their sightings to the HKBWS.
Beyond the Tai Po Kau Nature Reserve, the scrub and long grass of the IBA’s higher slopes of Tai Mo Shan offer habitats to more birds of scientific interest and conservation concern. They include a small streaky brown bird identified in a 2010 paper by Hong Kong ornithologists Paul Leader and Geoff Carey, among others, as a separate species new to science, based on their morphological, vocal, and genetic study.
The bird, now named the Chinese Grassbird, or Chinese Grass-babbler, had been considered a sub-species of the Rufous-rumped Grassbird (Graminicola bengalensis) until the 2010 study found it differed enough to be regarded as separate and recommended that the Rufous-rumped Grassbird be “split” into the Chinese Grassbird (Graminicola striatus) and Indian Grassbird (Graminicola bengalensis).
A 2012 report of a survey conducted by the AFCD’s Bird Working Group estimated there were 490 Chinese Grassbirds in Hong Kong, and highlighted the importance of maintaining the grassland habitat, with some woody vegetation, for its conservation.
The Chinese Grassbird is listed as vulnerable in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, though a 2021 study involving researchers from Kadoorie Farm and Botanic Garden and HKBWS found it more widespread in Mainland China than records had previously indicated and recommended it should be classed as near-threatened.
This latest study estimated there were between 80 and 490 Chinese Grassbirds in Hong Kong, described as its “stronghold”.
As such, long grasses found across Hong Kong’s uplands – shrinking in some parts due to colonisation of shrubs and trees in the natural process of succession – have vital ecological importance for the Chinese Grassbird and other birds, such as Prinias, that rely on these areas for food, protection, and nesting sites.
Living with humans 1
Natural high-flyer: as many as 2,000 Black Kites (Milvus migrans) reside at least part of the year in Hong Kong, one of Asia’s largest concentrations. Photo : Wei Shyy
Life in Hong Kong appears to suit the Black Kite, lord of the skies above the city. But its majestic presence should not be taken for granted
Black Kites, the most frequently sighted of 27 species of raptors found in and around the city, are an iconic sight as they circle high on the thermals in the sky, glide among high-rise office buildings, or stoop suddenly when eyeing food along coastlines.
Of the estimated six million Black Kites (Milvus migrans) worldwide, as many as 2,000 reside – at least part of the year – in the city and its rural landscapes, making Hong Kong and its environs host to one of the largest concentrations of the bird in Asia. These are the eastern form of this raptor, also known as the Black-eared Kite (Milvus migrans lineatus).
Believed by many experts to be the world's most abundant species of Accipitridae, which includes other birds of prey such as eagles, hawks, buzzards, and harriers, the Black Kite plays a vital role at the top of the food chain.
“Kites are top predators so are very important in terms of ecology. They will feed on rodents, reptiles, and other birds and also scavenge, removing dead animals from the environment,” said Dr Gary Ades, of Kadoorie Farm and Botanic Garden (KFBG) in the New Territories.
Ades is Head of Fauna Conservation at KFBG, which focuses on flora and fauna conservation, organic agriculture, environmental education and sustainability in Hong Kong and beyond. Among its many conservation endeavours, KFBG runs a raptor rescue centre and the Jim Ades Raptor Sanctuary, set up in 1994.
Ades’ father, Major Jim Ades, rescued and cared for birds of prey in Hong Kong’s first private authorised rehabilitation programme in the 1980s and 1990s. He also helped in the early development of KFBG’s Raptor Sanctuary and provided its first birds of prey.
Black Kites can live up to 24 years, with a large local population noted since at least the 19th century. However, their abundance and impressive ability to adapt to urban environments should not be taken for granted, with some bird-watching groups fearing that the ubiquity of these magnificent raptors – with wing spans typically as wide as 150cm – can instil complacency with regard to their conservation status.
The bird, which is brown rather than black despite its name and has a plaintive, whinnying call, is the focus of attention for the Hong Kong Bird Watching Society (HKBWS)’s Kite Research Group. The small team, currently numbering eight and a convenor, has been observing this raptor for two decades. They do so by studying and monitoring the local population and breeding conditions through monthly kite surveys and an annual breeding survey.
From the data gathered, the group can keep track of any changes in the population, and be ready to measure the impact of habitat destruction, whether through urban development or natural disaster.
“The numbers are more or less stable,” said Beta Yip Chi-lap, a longstanding group member. “There are about 200 individuals in the summer and about 2,000 by the spring, mostly divided between Stonecutters Island and Magazine Gap [on Hong Kong Island].”
No one is sure why the numbers fluctuate so much seasonally, or where many of the birds migrate to in the summer. “We still don’t know where they go. There has been no tagging or tracking undertaken on a large scale so we don’t have a lot of data,” Yip said.
But recent surveys in Taiwan indicate the Black Kite follows a coastal migratory route from northern China to Guangdong and the Pearl River Delta.
Karin Chin first became involved in the HKBWS group as a biology undergraduate at the University of Hong Kong. She said the shortage of high-level research data locally is due to the kite not being considered of strong enough conservation concern.
“Raptors like the Black Kite are an indicator species but the Black Kite is less affected by human development and loss of habitat because they are primarily scavengers rather than predators,” Chin said.
One of their major habitats is Yeung Chau, a five-hectare uninhabited island opposite Sai Kung Pier in the New Territories, where over 400 kites have been recorded. There, they share their space with the much rarer White-bellied Sea Eagles (Haliaeetus leucogaster).
On the hunt: a White-bellied Sea Eagle (Haliaeetus leucogaster) flies low over water with talons outstretched, ready to grasp a fish. Photo: Wei Shyy
Up to 15 pairs of the sea eagles have been recorded in Hong Kong, the only place that hosts a regular population of the National Grade Class II protected species in China. Most of these birds are spotted in Yeung Chau and on Chau Kung To (Sunshine Island), off the coast of Lantau, where they soar above the island’s pink granite cliffs.
Kites also share the local environment with less readily seen raptors, such as the Crested Serpent Eagle (Spilornis cheela) and Oriental Honey Buzzard (Pernis ptilorhynchus), birds that the kites may be seen mobbing when they intrude their air space.
Meanwhile, in winter, Hong Kong’s Deep Bay area is visited by three giant birds of prey: the Greater Spotted Eagle (Clanga clanga), endangered Eastern Imperial Eagle (Aquila heliaca), and Cinereous or Black Vulture (Aegypius monachus). Hong Kong is also home to several species of owl, such as the Brown Fish Owl (Ketupa zeylonensis).
But as scavengers, it is the Black Kite that has adapted particularly well to Hong Kong’s mix of urban, mountain, and marine environment. They are able to feed on dead fish in the harbour, but will also take young feral pigeons from tower block nests.
Black Kites still face challenges and threats, both in the natural and urban environment. Natural threats include Masked Palm Civets, snakes, and other birds of prey that might predate young birds and eggs in the nest. The man-made threats include overhead power lines and mirrored windows.
KFBG has run education programmes requesting that owners and tenants of high-rise office blocks place small black kite-shaped stickers in the windows of their offices to prevent kites from colliding with the glossy reflected images of the surrounding environment. Reflective glass may look attractive to architects but is a hazard for kites and other birds.
Ades also reported that some kites had been delivered to the KFBG raptor rescue centre after collisions with buses.
Despite being prevalent above the city, Black Kites are also threatened by loss of woodland habitat. Chin said: “They have adapted to urban life but they still need large mature trees to roost in.”
Both Chin and Yip point to the experience in Taiwan, which demonstrates that despite the adaptability and abundance of the Black Kite, its population remains vulnerable to change.
The bird had been widely distributed in the low-altitude plains and hills across Taiwan, and categorised as “common” when the first systematic bird survey for the island was conducted in 1973.
However, by 1991, ornithologists had noted that the Black Kite had rapidly disappeared during the 1980s, reduced to only 175 individuals inhabiting only 39 per cent of its previous range. The bird still has only limited distribution within Taiwan due to that dramatic population decrease.
For this reason, Yip and Chin say Hong Kong’s Black Kites and their needs must be appreciated and should be the subject of more research interest.
The group would like to do more tracking projects, and Chin suggested this could include tagging the birds with miniature cameras so their behaviour can be more closely observed.
Until more detailed research is done, the exact habits and migratory journeys of these most adaptable of raptors will remain a mystery. But on almost any day in Hong Kong we have the chance to look up and see them circling on high, and wonder.
Aerospace lessons from natural flyers
As a mechanical and aerospace engineer, Professor Wei Shyy, President of Hong Kong University of Science and Technology, finds inspiration in nature’s flyers.
The keen bird photographer is fascinated by what science can learn from birds, bats, and insects, which outperform man-made aircraft in aerobatics and handling unpredictable environments, as he points out in the introduction to his collection of photographs, Flight in Sight.
For example, the roll rate of an aerobatic plane is about 720 degrees per second compared with an excess of 5,000 for the Barn Swallow. Meanwhile, raptors can often accelerate and turn at faster rates than the most advanced military aircraft.
“More insight can be gained from understanding natural flyers for the development of micro-scale flight vehicles, which can significantly benefit from flapping wing aerodynamics,” Shyy said.
Meanwhile, he hopes his photographs will also inspire an appreciation of their natural beauty, and of their presence around us.
Living with humans 2
Frequent flyer: a member of Hong Kong’s House Swift (Apus nipalensis) population, many of whom reside at the Chinese University of Hong Kong. The swift group of birds typically never land on the ground, eat on the wing, can attain super-high flight speeds, and are capable of travelling huge distances. Photo : John Holmes
It is not just students who congregate at Chinese University of Hong Kong (CUHK)’s University Square on the Shatin campus in the New Territories. Above them, young people can marvel at the sight and sound of hundreds of House Swifts (Apus nipalnensis) that they share their space with – the largest colony of these birds in Hong Kong.
It was soon after CUHK’s Main Library was built in the 1960s, adjacent to the square, that swifts took up residence, finding small bare concrete spaces within the eaves of the library roof to be particularly suitable for their nests.
House Swifts spend much of the day soaring on the wing, dining in mid-air on a range of flying insects. Only when they return to their elevated nesting sites, do they pause. They do not land on the ground, with their claws and short legs adapted for clinging to rock and launching back into flight from on high.
These birds, a member of the Apodidae family, and Barn Swallows, of the Hirundinidae family, traditionally nest under eaves, beams, and balconies in older village houses and tenement blocks in Hong Kong.
Unlike Common Swifts (Apus apus) in Europe that are present only in summer, they can be seen in Hong Kong throughout the year. However, some migrate and, along with the Barn Swallow (Hirundo rustica), can be spotted in large flocks of as many as 1,000 birds gliding over the fish ponds in the Deep Bay area of the New Territories during the spring and autumn migration periods.
While the House Swift population across Hong Kong appears to be stable, they face many challenges, most notably from redevelopment and building renovation works, new materials used in construction, as well as from insecticides that diminish their food supplies.
Hygiene concerns have also threatened the population. “Droppings from nests are often considered as a nuisance and disease-causing, especially after outbreaks of avian flu, which caused deliberate and illegal destruction of House Swifts’ nests in old urban districts,” said John Chung Chun-ting, whose MPhil research at CUHK on birds’ diets involved a DNA investigation of those droppings.
However, the Hong Kong Bird Watching Society (HKBWS) explains in its public education that swifts and swallows pose no serious threat. Of 74,000 dead birds of all species collected by the Hong Kong government’s Agriculture, Fisheries and Conservation Department between 2009 and 2014, only 41 were confirmed to have avian flu. At the time of writing, no instances of House Swifts with the disease have been recorded since then.
Against such modern-day concerns, there is a traditional belief in Chinese culture that the presence of a swift or swallow nest under the eaves of a building brings good fortune to the owner. “Therefore many property owners show sympathy towards the nest-building swallow and swift,” Chung said.
One example of how far such respect can go and how nature can be successfully accommodated in urban design was the redevelopment of CUHK’s Main Library, where the swifts lived.
Their homes could have been in jeopardy when the university needed to extend the library, a project it completed in 2012. Instead, their wellbeing was built into the plans from the start. This involved an elaborate scheme to “migrate” the birds from one side of the building to the other.
Fung Siu-man, director of the Campus Development Office, and Thomas Yuen, its project manager, explained that on advice from ecologists, nylon canvas was used in stages to block their old homes, while artificial nest boxes were offered and accepted as interim alternatives, giving them time to build new nests.
The operation, overseen by the Estate Management Office, was successfully conducted two years in advance of the works.
The project not only provided the birds with new homes, but was also designed to assure their safety when glass walls were chosen for the extension. Glazing with a dotted pattern was tested over several months to make sure the swifts did not fly into it, with nets erected below the test area to catch any injured bird. None were found.
“We call it bird-friendly glazing,” Yuen said. “Up to today, there has been no incident of birds flying into the glass walls.” The glass chosen was also comfortable for library users, by providing shade from glaring sunlight.
Yuen estimates that there are now around 200 swifts at home in the library’s eaves, and with no noticeable decline since the redevelopment.
Fung said: “They are very spectacular. The birds come out of their nests in the morning. In the late afternoon, at about 4pm, the sky is full of them, coming home. It is a fabulous sound.”
He explained that taking care of the swifts reflected the university’s vision and mission. Masterplans for development include the principle of conserving places and landmarks of historical value, and maintaining a sustainable campus with strong biodiversity. The swifts qualified on both counts.
“The history of the swift is an important part of the plaza and library building, and collective memory of students and alumni,” he said. The project to save the birds cost around HK$200,000, which Fung and Yuen regard as modest for the benefits gained for the birds, the biodiversity of the campus, and its human users.
While swifts have only chosen the library for their nests, nature is taken into consideration across the planning of all new buildings at the university. Sky gardens and vertical greening are now common features, with green spaces around the buildings designed as extensions of the existing natural landscape.
“We are very proud of the campus,” Fung said. “We have university education, and students living with nature and the landscape.”
In-flight meals with a difference
MPhil graduate John Chung Chun-ting was inspired by his special ties with the House Swift, developed as a Chinese University of Hong Kong (CUHK) student, to make it the subject of his research into what DNA tracing can tell us about the diets of the birds.
He was also able to take advantage of the ready supply of bird droppings around CUHK’s Main Library for his study, completed in mid-2020 with the School of Life Sciences.
The research, conducted with Dr Chan King Ming and published in 2021, revealed Hong Kong’s House Swifts enjoy a diet dominated by Hymenoptera (ants, bees and wasps), Hemiptera (for example, plant bugs) and Diptera (flies and mosquitoes), affirming the birds’ role in stabilising insect populations, including pests such as mosquitoes, wasps, and termites.
“House Swifts are aerial feeders so they rely on food available in the air,” said Chung, who majored in Environmental Science and is now a PhD student at the University of Hong Kong. “They chase their prey at speed and enjoy their meal by opening their mouths.”
The ants that Chung found had been caught during the insects’ breeding season when they perform their “nuptial flight”, during which winged queen and male ants fly from their nests for mating, before establishing a new colony.
More alarming was the fact that within the droppings they found the notorious invasive red imported fire ant (Solenopsis invicta), which has been present in Hong Kong since 2005. “The presence of this species implies nuptial flight could be a possible reason for the quick spread of this ant in Hong Kong,” he said.
Chung’s passion for the House Swift is echoed among members of the Swift and Swallow Research Group in the Hong Kong Bird Watching Society (HKBWS). The research group was established in 2003, and since then has conducted annual surveys of their nests.
Around 100 volunteers participated in the 2019 survey across all 18 districts in Hong Kong. About 2,000 active nests were found in more than 160 sites.
Chung believes the numbers of swifts to be stable, despite the need for more vigilance to protect them. More awareness that people and birds can live in harmony, as shown at CUHK, would also help.
For Chung, watching large flocks of swifts return to their nests before dusk was one of his most enjoyable memories of his alma mater. “They are among members of CUHK, thus have a special bond with me,” he said.
TAKING A LEAD ON BIODIVERSITY
Some of the major education, government, and community organisations that provide expertise and knowledge related to Hong Kong’s biodiversity, ecology, and environment.
Research and Education
Chinese University of Hong Kong
City University of Hong Kong
Education University of Hong Kong
Hong Kong Baptist University
Hong Kong University of Science and Technology
University of Hong Kong
Many thanks to the following for their photographs.
- Tim Boucher
- François Brassard
- Robert Ferguson
- Katherine Forestier
- John Holmes
- Pete Kline
- Sharne McMillan
- Sung Yik-hei
- Professor Wei Shyy, President, Hong Kong University of Science and Technology, Flight in Sight ebook and website
- Martin Williams
- Michelle & Peter Wong
- Sherman Yeung
- Agriculture, Fisheries and Conservation Department
- Kadoorie Farm and Botanic Garden
Pictures also sourced from:
- Creative Commons, Wikimedia, licensed under Attribution-Share Alike 3.0 Unported licence (hongshanyingyue)