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).