As global travel and trade increase, so has the numbers of species spreading beyond their natural ranges. Introduction of alien species, intentionally or unintentionally, as a result of human activities may lead to the extinction of native species via interbreeding, predation, resource competition or the spread of disease. Pangolins are widely trafficked (S. Heinrich et al., 2017, The Global Trafficking of Pangolins: a Comprehensive Summary of Seizures and Trafficking Routes from 2010–2015, TRAFFIC South-east Asia, Selangor, Malaysia), and with the Chinese government improving wildlife protection and strengthening law enforcement the release of confiscated pangolins by law enforcement departments is increasing. There have been at least 10 cases of the release of confiscated pangolins into the wild in China since 2016, including one case each in October 2016, January, July and September 2017, May, June and August 2018, and three cases in July 2018 (mp.weixin.qq.com/s/zWQ27feivJiO4bBjZPKvFQ). In at least five cases the release was of Manis javanica, which is native to South-east Asia, including cases in Zhanjiang city, Hengyang city, Wenshan Zhuang and Miao Autonomous Prefecture, and Xishuangbanna Dai Autonomous Prefecture.
Although releasing confiscated species into their natural habitats is potentially important for species conservation, releasing wild animals beyond their natural range is a complex undertaking that requires careful consideration and scientific support, without which release may not only fail to achieve the desired results but also harm the local ecosystem. In China M. javanica is native only in Menglian and Menghai counties, Yunnan Province (Wu et al., 2005, Acta Zootaxonomica Sinica, 30, 440–443). Most pangolins confiscated in China have been transported outside their range, from other regions or countries.
We believe that M. javanica should not be released into most regions of China, for the following reasons: (1) Most regions have a markedly different climate from that of the species' natural range, and pangolins have poor adaptability, impeding their survival outside their natural range (Wu et al., 2004, Chinese Journal of Applied and Environmental Biology, 10, 456–461). (2) M. javanica is a K-strategist, and thus the establishment of a sustainable population through the release of a few individuals outside their natural range is unlikely. (3) The species often carries multiple parasites or pathogens (Yang et al., 2010, Journal of Economic Animal [sic], 14, 22–25; Zhang et al., 2017, Zoo Biology, 36, 387–396) and therefore release into new areas carries the potential risk of introducing parasites or pathogens. (4) As an alien species M. javanica may have adverse effects on local ecosystems through predation of, or competition with, native species such as Manis pentadactyla (Wu et al., 2005, Acta Zootaxonomica Sinica, 30, 440–443). (5) As the original source of confiscated pangolins is generally unknown, individuals may be released outside their source area, with the potential for genetic contamination of native populations.
Several Chinese institutions have made progress in conservation breeding research using confiscated M. javanica. The species survives well in captivity, and dozens of individuals have successfully mated and reproduced (Zhang et al., 2015, Folia Zoologica, 64, 129–135; 2017, Zoo Biology, 36, 387–396). We recommend that the Chinese government establishes a pangolin rescue and breeding center for this rare species. Meanwhile, rescued individuals could be used to conduct conservation and biological research and to establish an ex situ population. In the future an ex situ population could be used for restoration of the wild population within its natural range.
