Biodiversity loss is one of the top threats in Anthropocene. It is estimated that the current species extinction rate is at 1,000 to 10,000 times the background natural rate (Chivian & Berstein, 2008), because of increasing environmental impacts from anthropogenic activities, including global warming, habitat loss, introduction of exotic species (Thomas et al., 2004). As the extinction of every species potentially leads to the extinction of others in the ecosystem matrix, we may unravel snowballing extinction cascades in the future if proper conservation management is inadequate.
Since last century, many captive breeding programs have been launched to salvage endangered species from imminent extinction (Frankham, 2008). They are vibrant in the highly diversified forms: a university lab, a joint conservation group or a zoo. They have been targeted to serving for a wide range of conservation purposes: (1) the crucial goal in maintaining genetic integrity of threatened species; (2) the pivotal role of translocation and re-introduction programmes that restore wild population (Grueber et al., 2015); (3) educating people of the importance of wildlife conservation; and (4) substantiating in-depth research opportunity for future applications.
Captive management is utterly important when the species can no longer sustain the population itself in the wild. Besides the human activities, natural catastrophes such as strong predation pressure, diseases and food shortage can also endanger wild species to an unsecured population. For example, pink pigeon (Nesoenas mayeri) once experienced a population shock down to 10 individuals, thus is enlisted in IUCN Critically Endangered in 1994. They suffered from introduced invasive species (Swinnerton, 2001) and intense food competition (Jones & Owadally, 1988). The compounding effect of captive breeding and reintroduction have been successful to bring back the survival likelihood. It has been downlisted to Endangered and may become eligible for further downlisting in the future. Captive breeding is beneficial to concentrate the resource and management effort, as compared to in-situ conservation, especially when the population is small and vulnerable to natural chance events. Other successful reintroduction examples include scimitar-horned oryx, Californian condor and golden lion tamarin.
The rationale behind the educational purpose of a captivity such as zoos and marine parks is the created affective connections bridging the nature and visitors. In compared to alienated forms of conservation outreach, such as propaganda and leaflets, the actual experience spending with an animal quickly strengthens the bonding and thus raise a higher compassion to save the endangered animals. When reports find out that there are positive effects of zoos on cognitive and affective characteristics (Luebke et al., 2016), captive management breaks the estrangement between public and wildlife, and affirms the community engagement of conservation.
The success of species conservation depends much on our understanding of their behavioral ecology, habitat and reproductive biology. Captive breeding enables researchers and conservationists to study and experiment the mating success and optimal environmental factors that are most favorable to the species. Especially when certain endangered species is endemic and possesses unique physiology, such as keel-scaled boa in Round Island (Casarea dussumieri) (Bloxam & Tonge, 1986), captive breeding safeguards a better prospecting future of the conservation of the species and its closely related relatives. Further genetic and molecule tools can enable us to minimize inbreeding and maintain the genetic diversity by implementing carefully planned captive management, increasing the chance of successful adaptation to the environment upon reintroduction or translocation (Witzenberger & Hochkirch, 2011).
The three pillars of conservation, education and research in captive management are entwined to conserve the endangered species. However, the effectiveness of captive breeding stirs up some debate as more limitations and inadequacies are untangled.
Captivity may be time consuming but rewarding less, failing to improve the conservation status or mitigating the declining population. For example, the habitat of Hainan gibbons (Nomascus hainanus) is severely fragmented and degraded by infrastructure development (Cawthon Lang, 2005). However, their reproduction biology is sophisticated and discerns great effort. Without a proper mating ground, their lack of territories is a prominent reproductive barrier in the wild (Zhou et al., 2008). Although attempts have been made to breed Hainan gibbons in captivity, all have been failed and the captivity plan is abandoned. Currently there are no Hainan gibbons in captivity (Geissmann, T. & Bleisch, 2008).
Latest findings report that students demonstrate no positive learning outcomes at all (Jensen, 2014). The paper concludes, that zoos fail to nurture proactive conservationists among students and empower the pupils to take ameliorative actions. This research conflicts with the common belief that zoos can function as an important education source. The possible reason behind is the differential management of educational programmes in different places, and the report is locally-targeted. It sheds light on the limitation that different zoos take different approaches in delivering education, while some succeed, some have week efforts.
There are disproportionate efforts allocated to certain species because of an anthropocentric view of conservation effort. A better-known example is the ‘panda-centric conservation’ in which Chinese government has invested tremendous conservation funding for its captive management. Giant panda costs each hosting captivity an average of 2.6 million dollars a year, and the cost can compound to 4 million when cubs are arisen (Warren, 2006). The great financial commitment exerts strong burden to the government, NGO and the public. As a result, ‘flagship species’ is the conservation marketing strategy that attracts public awareness and financial donation. However, it potentially skews the conservation priorities in sole humans’ favour and the detrimental species receive less attention (Ducarme, Luque & Courchamp, 2013). Particularly when the panda is successfully downlisted to Vulnerable in IUCN, the flagship may disappear and poses negative impacts on the attitudes of the conservation stakeholders (Simberloff, 1998).
Captive management is undoubtedly an indispensable tool to preserve a ‘insurance population’ for endangered species. However, the daunting crisis of species extinction must be faced squarely and ex-situ conservation is only the last resort to rescue those species in the edge. In-situ conservation, habitat preservation and better wildlife management must be prioritized and captivity is not an excuse to avoid them.