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Dear Feedback,

I would like to refer to the front-page article ‘The empty forest’ and the related piece ‘Re-introduction: setting the ball rolling ….’ on p.16 in the last issue of Porcupine! (issue 25) by Dr. Richard Corlett. Richard points out that many forest species are missing in Hong Kong forests and suggests that a programme of planned reintroductions would have many benefits such as restoring the ecological processes, enhance public awareness, improve survival prospects of the species concerned and reduce the risk of invasion by exotic species. It seems to make good sense but on closer examination of the issue, it is not as simple and straight-forward as Richard suggests (also refer to Lau, 2002). The IUCN Re-introduction Specialist Group has produced useful guidelines (IUCN/SSC Re-introduction Specialist Group, 1998) that cover the concepts, design, feasibility and implementation of wildlife reintroductions and I will not go into the detail of these here. Success rates are actually quite low and there are many risks associated with reintroduction projects, such as outbreeding depression and disease transmission (Dodd & Siegel, 1991; Reinhert, 1991).

Restoring ecological function is important but the case put forward by Richard is weak because most of our knowledge on ecological function is on degraded Hong Kong forests rather than the target ‘pristine’ forests. For instance, we know Hong Kong lacks many dispersers of large seeds but do we know exactly which species is (are) needed to disperse the seeds of, say Beilschmiedia fordii, and whether this disperser can survive in Hong Kong’s young, patchy forests? Hence, the Phase 1 species are easy-to-establish ones rather than species that can fill a particular ecological role that is vacant. Moreover, many other groups besides mammals and birds also carry out important functions and we know even less about them.

Reintroductions are very costly if carried out properly and would require long-term monitoring to determine the results. Even for the easy Phase 1 species, it would require a lot of resources, yet the conservation gain (assuming success) is disproportionately small because all the proposed species are common and widespread in the region. Moreover, whether or not some of them (e.g. the Grey-cheeked Fulvetta) need reinforcement is too early to tell because most the listed species have only been in Hong Kong within the last twenty years or so. Quite a few have expanded their local range and some seem to be doing so. Shouldn’t we give nature more time?

Another important point is that Hong Kong forests are not completely isolated. The forest at San Kwai Tin and the Wutongshan forest in Shenzhen are only separated by the few-metre-wide headwater of the Shenzhen River. The latter is connected to other hill forests further north. Natural re-colonization has occurred in Hong Kong forests. On a local scale, quite a few forest species have spread from refuges to certain secondary forests in the last twenty years as the forests became more established. There are also cases of ‘cross-border’ colonization by birds and butterflies. The list is not long but one has to bear in mind the very short history of re-forestation, and the fragmentation of forests in the region. The other reason is that Hong Kong forests are still not mature enough for some species. This condition will change but it takes time for the young forests to mature, expand and join adjacent forest patches. Re-forestation under the Chinese Government’s ‘ecological forests’ scheme should link up many existing forest patches in the future. Then a larger scale re-colonization is possible.

In view of the many risks involved and the costly nature of reintroduction projects, extra care should be exercised when planning for these. The first step will be to gather rigorous scientific information. Research needs to be carried out in South China’s intact forests to see which species perform the ecological functions we want to fill. We also need to find out the exact requirements of the target species to determine whether existing Hong Kong forests (in terms of size, forest structure, food availability, predators/disease, etc.) are suitable.

Reintroduction is just one of many conservation tools and we need to prioritise them. Locally there are many urgent conservation issues that need to be tackled. For instance, we still lack a conservation policy; the vast majority of the important sites identified by the Biodiversity Survey undertaken by HKU remain unprotected, many marine species are still facing uncontrolled exploitation, and most invertebrate groups have yet to be inventoried. Reintroduction of several common and widespread species, i.e. Phase 1 in Richard’s articles, does not seem to be particularly pressing. Hong Kong biota is part of the South China region and we should not treat it in isolation. South China forests and the species they support are under immense threats. A lot of input in terms of funding, expertise, education, capacity-building and community development will be needed to reduce these threats. I think that in most cases, resources put into reintroduction projects could be better spent in in-situ conservation. There are obviously exceptions and we need to identify them based on hard data. That’s the alternative to ‘experimenting’ on an ad hoc basis, as Richard proposes.


Dodd, C.K.Jr. & Siegel, R.A. (1991). Relocation, repatriation and translocation of amphibians and reptiles: are they conservation strategies that work? Herpetologica 47: 335-350.

IUCN/SSC Re-introduction Specialist Group. (1998). IUCN Guidelines for Re-introductions. IUCN, Gland.

Lau, M. (2002). Captive breeding and translocation – is it the way forward for conserving endangered species? Living Forests 4:18-23.

Reinert, H.K. (1991). Translocation as conservation strategy for amphibians and reptiles: some comments, concerns and observations. Herpetologica 47: 357-363.

Micheal Lau



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