Introduction
Accelerated anthropogenic impacts and
fluctuating climate change are widely considered to be responsible for
the continuous loss of biodiversity (Dirzo et al., 2014; Koch et al.,
2006). Over the past three centuries, many mammals in China have
exhibited distinct population declines and shrinking distribution
ranges, likely associated with increasing human populations and climate
fluctuations (Wan et al., 2019).
Habitat loss, population decline or displacement, and even local
extinction of wildlife are caused by anthropogenic factors, including
overexploitation, agricultural development needs, urbanization,
deforestation and human-introduced diseases (Trombulak and Frissell,
2000; Rosser and Mainka, 2002; Hill and Hamer, 2004; Smith et al., 2006;
Mckee and Chambers 2011; Dirzoet et al., 2014;
Menon et al., 2015; Turvey et al.,
2017). Climate change, including warming, cooling and fluctuation, could
influence the survival of wildlife regionally, and distribution shifts
are the response that would most likely lead to local extinction
(Pearson and Dawson, 2003; Koch and Barnosky, 2006; Chen et al., 2011;
Hei, 2012; IPCC, 2014; Li et al., 2015). It is widely recognized that
human disturbances have the greatest impact on wildlife extinction, but
the contribution of climatic factors can reach up to 54% (Urban, 2015;
Sahajpal and Goyal, 2018). In addition, the interaction of climate
change and human interference could accelerate wildlife extinction (Wan
et al., 2019). Therefore, determining which specific factors have a
greater impact will influence conservation decisions.
The Chinese pangolin (Manis pentadactyla ) is a unique,
scale-covered mammal species that mainly feeds on ants and termites,
playing an important role in maintaining the stability of the ecosystem
(Sharma et al., 2020; Liu et al., 2020). China used to be one of the
largest consumer markets of pangolins and their derivatives in Asia
(Sharma et al., 2020). Scales of Chinese pangolin were used in
traditional medicine, and its meat was consumed as a luxury food in
China. In the past five decades, the distribution range of Chinese
pangolins has been rapidly shrinking, and the population has declined by
80%-90% in several provinces of China (Challender et al., 2015, 2019).
Severe hunting and poaching stress imposed by the local and
international pangolin trade across its distribution range have been
demonstrated to cause the accelerated decline of Chinese pangolins
during this time period (Nash et al., 2016; D’Cruze et al., 2018). The
government of China made positive efforts to protect this endangered
species, such as upgrading Chinese pangolins from National Level II
Protected Animals to Level I and removing the species from theChinese Pharmacopoeia in 2020, which strengthened the
conservation policy (National Forestry and Grassland Administration,
2020). Despite the enormous human influence, we still cannot ignore the
negative effects of climate change on the loss and alteration of the
Chinese pangolin habitat because climate change during this period was
also very drastic. The average global surface temperature increased by
approximately 1 °C, and extreme weather events occur more frequently
than before (NOAA, 2021).
Identifying the causes of local extinction is an indispensable step in
conservation practice (Mateo-Tomás and Olea, 2010). However, the
quantitative relationships between local extinctions of Chinese pangolin
and anthropogenic and climatic factors have not been evaluated. It is
difficult to quantitatively determine which variables are the main
factors due to the lack of
long-term monitoring
data. Local chronicles
data provide insight into the
roles of human impacts and climate change in causing local extinctions
of Chinese pangolins. For more than 3600 years, since the Shang and Zhou
dynasties, China has a long history of recording significant political
and natural events. Owing to its economic value (mainly for traditional
medicine or as a rare gift), unique characteristics and reactions to
human activities (curling up when threatened), sightings of Chinese
pangolin were likely to be recorded in historical documents. Therefore,
local chronicles (from province to district), official and formal
records such as Twenty-Four Histories , and Comprehensive
Mirror for Aid in Government could be used to track the changes in the
distribution of the Chinese pangolin. In addition, the History Database
of the Global Environment (HYDE) consists of historical population
estimates and land use metrics, in particular, the population count,
population density, cropland coverage and the degree of grazing, which
are human factors affecting the survival of wild animals. The time
coverage of the HYDE database is from 10000 BC to 2016 AD. Data from
1700-2016 have a 10-year resolution, and the spatial resolution reaches
0.5×0.5 arc degrees (approximately 50×50 km2)
(Goldewijk et al., 2017). Weather data reconstructed from the records of
δ18O in ice cores in the Himalayas and tree rings
worldwide exhibit a highly significant correlation with the average
temperature and can be used as a metric to assess climate change in the
Northern Hemisphere (Zhao et al., 2014; Shi et al., 2015). Benefiting
from the unremitting development and updating of historical databases of
the global environmental data (anthropic and climatic) and combining
local chronicles, we have an opportunity to identify the causes of local
extinctions of the Chinese pangolin to inform conservation actions that
target the species (Wen 2009).
Therefore, we used local chronicles of the Chinese pangolin in China and
combined them with quantified anthropogenic stressors (represented by
population counts, population density, cropland coverage and grazing)
and temperature variations (represented by holistic temperature and
regional temperature) through a generalized additive model (GAM) to
determine key causes of local extinctions in 1700-2000 (Wan et al.,
2019). Then, we lowered the temporal scale and built an extinction risk
model estimated by the maximum entropy algorithm to identify which
variables contributed to the extinction events in 1970-2000, relying on
much more accurate and detailed environmental data (RoDder et al., 2009;
Benito et al., 2009). Through principal component analysis, we further
determined the degree of variation of those variables. Finally, we used
rescue information from the wildlife rescue departments and Global
Biodiversity Information Facility (GBIF) database from 2000-2020 to
evaluate the threatened status of extant Chinese pangolin populations in
China. Learning from history, our research can have implications for the
conservation practices to protect Chinese pangolins in China now and in
the future.