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Vertebrates (pdf)
Big fierce animals in Hong Kong
In his classic textbook, Why Big Fierce Animals are Rare, Paul Colinvaux (1978) explains why large carnivores necessarily live at much lower densities than their prey. For most of the world, however, it is not ecological necessity, but direct human impact that explains the rarity - or, in an increasing number of places, complete absence - of big fierce animals. They are killed because they threaten us or our livestock, or because they look as if they might, or simply because they are "bad animals". The history of China could be deduced from a comparison of large carnivore distribution maps at intervals over the last 10,000 years. Robert Marks (1998) attempts this for tigers in southern China in his book, Tigers, Rice, Silk and Silt.
If big fierce animals - BFAs from now on - are history in Hong Kong, why concern ourselves with them? The fuss caused by one juvenile crocodile in Yuen Long shows that even the most fervent proponent of reintroduction is unlikely to have much success with a "Bring back the BFAs" campaign. The answer is that we cannot hope to understand the ecology of Hong Kong today without knowing more about the environment in which the flora and fauna lived before the overwhelming human impacts of the last couple of millennia. BFAs were a key element of that environment, not just because they killed stuff, but also because they modified the behaviour of their prey - the so-called 'ecology of fear'. By influencing the numbers and behaviour of herbivores, carnivores have an indirect impact on the structure of plant communities. Equally important may be the influence of large carnivores on the abundance of the smaller carnivores, such as civets, which are the main predators of birds and other small vertebrates. The removal of large carnivores can therefore have major consequences for the rest of the community as the effects propagate from level to level down the food web, from top carnivores to plants, in a "trophic cascade". Unfortunately, we currently know far too little about the complexities of tropical food webs to predict what the impact of the loss of particular carnivore species will be.
The ultimate BFAs are the big cats, of which the tiger (Panthera tigris, 70-250 kg) and leopard (P. pardus, 30-70 kg) visited Hong Kong well into the last century. By that time, the largest prey species available were muntjacs and wild pigs but, given the opportunity, tigers specialize on bigger prey, such as the sambar deer (Cervus unicolor), which must have been here in the past. Each tiger needs about 50 large ungulates a year (Karanth et al., 2004), so there can never have been many tigers in Hong Kong. The leopard, in contrast, is the ultimate generalist. They take more monkeys than tigers do, and the commonest items in the scats of leopards on the outskirts of Mumbai are dogs and rodents (Edgaonkar & Chellam, 2002). A small population of leopards would probably thrive in modern Hong Kong but, although they would soon eliminate the feral dog problem and put the macaques back in the trees where they belong, they are a little too dangerous for comfort.
There is a big size gap between the leopard and only surviving felid, the leopard cat (Prionailurus bengalensis, 1-4 kg), and historical records are no help in filling it. Hong Kong is well within the present range of the clouded leopard (Neofelis nebulosa, 10-23 kg), however, so this species is a reasonable guess. Clouded leopards are at least partly arboreal and take medium-sized prey, such as macaques, muntjacs, pigs and civets. They do not appear to pose a threat to people, but they need forest and have large home ranges (> 20 km2) for their size (Austin & Tewes, 1999), so we will have to wait a few decades before even thinking about (re)introducing this species. More practical would be the Asiatic golden cat (Catopuma temminckii), which was present in southern Guangdong until recently (Gao, 1987), although at 8-16 kg it is not really a BFA.
The Asiatic black bear (Ursus thibetanus, < 170 kg) is an undisputed BFA. Hong Kong is well within the recent historical range for this species but, like tigers and leopards, a bear reintroduction would probably be too dangerous to people. Black bears are more herbivores than carnivores, with a passion for Fagaceae fruits, but they can and do kill muntjacs, serow and wild pigs (Hwang, 2003).
Dholes (Cuon alpinus, 10-20 kg) are not BFAs as individuals, but even tigers avoid a large dhole pack. In contrast to the big cats, but like other dogs, dholes do not deliver a killing bite, so large prey die from shock or loss of blood as a result of multiple injuries. There are historical records for this species in Hong Kong and a few small packs could perhaps survive here today if reintroduced, living on muntjacs, wild pigs and rats.
BFAs do not have to be mammals and it is a reptile, the Burmese python (Python molurus), that is the biggest, fiercest animal present in Hong Kong today. Stomach contents of these snakes have included porcupines, muntjac, wild pigs, civets and even leopards (Daniel, 2002). A really large one could kill, if not swallow, an adult human. And don't struggle too hard - they are a protected species in Hong Kong. The locally extinct water monitor (Varanus salvator) is not usually seen as a BFA, but they can reach a length of 2.5 m in some parts of their range. This is not much smaller than the Komodo dragon (V. komodoensis), which has occasionally killed people, and water monitors themselves have taken macaques and small deer. Skeletal remains of the false gharial (Tomistoma schlegelii) have been found in the Pearl River. This crocodile is often considered a fish-eater, but there are reliable accounts of adults, which can exceed 5 m in length, taking riverbank mammals as large as macaques. Finally, Hong Kong is well within the historical range of the largest reptile of them all, the saltwater crocodile (Crocodylus porosus). A 7-metre "saltie" would be a threat to anything up to and including a tiger.
Bibliography
Austin, S.C. & Tewes, M.E. (1999). Ecology of the clouded leopard in Khao Yai National Park, Thailand. CAT News 31: 17-18.
Colinvaux, P. (1978). Why Big Fierce Animals are Rare: an Ecologist's Perspective. Princeton University Press, USA.
Daniel, J.C. (2002). The Book of Indian Reptiles and Amphibians. Oxford University Press, Mumbai, India.
Edgaonkar, A. & Chellam, R. (2002). Food habits of the leopard, Panthera pardus, in the Sanjay Gandhi National Park, Maharashtra, India. Mammalia 66: 353-360.
Gao, Y.T. (1987). Fauna Sinica: Mammalia. Vol. 8. Carnivora. Science Press, Beijing.
Hwang, M.H. (2003). Ecology of the Asiatic black bear and people-bear interactions in Yushan National Park, Taiwan. Ph.D. thesis, University of Minnesota.
Karanth, K.U., Nichols, J.D., Kumar, N.S., Link, W.A. & Hines, J.E. (2004). Tigers and their prey: predicting carnivore densities from prey abundance. Proceedings of the National Academy of Sciences of the USA 101: 4854-4858.
Marks, R. B. (1998). Tigers, Rice, Silk, and Silt: Environment and Economy in Late Imperial South China. Cambridge University Press, UK.
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