Discussion
Combining multiple perspectives, scales and methods, local chronicles revealed that anthropic and climate variables were significantly associated with local extinctions of Chinese pangolin in China. In summary, the substrates that caused extinction were intensive human interference, and drastic climatic fluctuations induced by global warming accelerated the extinction process. Hunting, farming and grazing conducted by humans caused population decline and extinction of wildlife. The anthropic pressure to which Chinese pangolins were exposed might have exceeded their tolerance threshold. Through the interaction of human and climate disturbances, more drastic climate change in recent years has accelerated the extinction rate of Chinese pangolins (Li et al., 2018). Our results implied that human disturbance and climate change codetermined the current distribution of Chinese pangolins. The population and distribution range of the Chinese pangolin will continue to shrink with highly intensive human activities and drastic climate change.
Local chronicles served as long-term monitoring data and provided important insights revealing the association of anthropic and climatic variables with the local extinctions of the Chinese pangolin. The Chinese pangolin was once a widely distributed species in China and is now only distributed in provinces south of Yangtze, including Fujian, Guangdong, Guangxi, Yunnan, Guizhou, Hunan, Hainan and Taiwan (Allen and Coolidge, 1940; Jiang, 2015). From the 1960s, the population of the Chinese pangolin decreased by 88.88%-94.12% and disappeared from more than half of its distribution range in southern China (Wu et al., 2004). Historical data have helped identify the driving forces of local extinctions in the long term and have contributed to the generation of efficient conservation strategies for Chinese pangolins. However, due to the limitations of historical environmental data, hunting and poaching pressures could not be accurately assessed because measurements of population density and counts do not exhibit correlation with them in highly urbanized areas (Nash et al., 2016). This could be the reason why GAMs were unable to detect the significant influence of population density and count.
Along with population growth, trade and consumer demand have become major threats to the survival of Chinese pangolins and can be represented by the total population count (Challender et al., 2015). Pangolin scales were thought to cure evil sores, malaria, and mastopathy according to traditional Chinese medicine (e.g. Compendium of Materia Medica) and pangolin meat was considered a luxury food item (Challender et al.,2015). In the past, China was one of the largest consumer markets in Southeast Asia, and a growing population has led to increasing demands for pangolin products. In addition, population growth exacerbates hunting, poaching, and land utilization, which directly leads to the decline of pangolin populations, habitat loss and fragmentation, followed by local extinctions (Turvey et al., 2017).
Based on the results of the principal component analysis, the variation in climate data was much greater than that in anthropogenic data, implying that the Chinese pangolin is more easily affected by climate change. The Chinese pangolin is a homotherm and accelerated global warming and temperature fluctuations may affect them negatively. First, the density of Chinese pangolins may change at given locations, and the ranges of species may shift either poleward or up in elevation as species move to occupy areas with climates within their metabolic temperature tolerances. Second, because many natural history traits of species are triggered by temperature-related cues, changes could occur in the timing of events (phenology), such as migration and breeding. The synergism of rapid temperature rises and human stressors, in particular habitat destruction, could easily disrupt the connectedness among species and lead to a reformulation of species communities, reflecting differential changes in species, and to numerous extirpations and possibly extinctions (Root et al., 2003). In addition, global warming increases the probability of extreme weather and wildlife diseases. East Asia is subject to increased warm and dry extremes, and southeast Asia experiences a higher probability of extreme rainfall in spring (Lee et al., 2012; Thirumalai et al., 2017). The risk of contracting diseases (especially vector-borne diseases) both in humans and animals increases as a result of global warming. Species extinctions may be due to changes in habitats or the transport of livestock which facilitates the movement of viruses and arthropods (especially ticks) from one place to another (Black et al., 2008; Dhama et al., 2013).
Their scattered distribution implies that the conservation practices of Chinese pangolins must depend on the efforts of local governments. Chinese pangolin populations with a high risk of extinction are spread over more than six provinces in China (Fig. 4), and 36.59% of high-risk populations are distributed in Guangdong, which is one of the most developed provinces in China. Therefore, the challenge is how to coordinate wildlife conservation and local economic development in Guangdong. Given this, we suggest strengthening population field investigations and accurately identifying the distribution range of Chinese pangolins. Further efforts to optimize the network of nature reserves to improve the conservation coverage of Chinese pangolins from the perspective of territory are required because the species has not received enough conservation resources in the past. An off-site conservation strategy is another workable solution to overcome conflicts between local economic development and small populations of Chinese pangolins (Vitt and Havens, 2004).
China has been strengthening its conservation policy for the Chinese pangolin. All illegal wildlife trade has been strictly banned to eliminate the excessive consumption of wildlife and ensure ecological security (NPC, 2020). In addition, the Chinese government strengthened the management of medicinal animal products, and pangolin scales were removed from the Chinese pharmacopoeia in 2020. Moreover, the Chinese government upgraded the designation of the Chinese pangolin to first-class national protected animals in the same year (National Forestry and Grassland Administration, 2020), indicating that this species and its habitat would receive stricter protection after the prohibition of the wildlife trade.
Future conservation practices may need to focus more attention on the assessment of small population viability and the subsequent population restoration. Excessive human exploitation and utilization of land resources lead to the fragmentation of the habitat of Chinese pangolins and suitable habitat patches and even national nature reserves with defined protection objectives usually present as “isolated islands” in a world dominated by human activities. Small populations are less stable and more susceptible to inbreeding depression and outside interference (Seth et al., 2021). Chinese pangolins are widely distributed, and it is feasible to establish ecological corridors between habitat patches that are close in proximity. However, species recovery among long-distance and isolated patches requires appropriate human intervention to save local populations. Artificial breeding, rewild and reintroduction are reasonable methods to guard against the extinction of small populations (Kuehler et al., 2000). In addition, based on an empirical analysis, the distribution mode of extant Chinese pangolins did not show a typical avoidance strategy for human settlements (Zhang et al., 2021; Wang et al., 2020). Residential and rural areas that overlap with pangolin populations should be targeted for efforts to improve awareness of the benefits of wildlife conservation (Zhang et al., 2021).