Discussion
The takin is a large montane species with a seasonal migration (Guan et al.,2013), and preference for habitat with forest cover and low human disturbance (Guan et al., 2015). The previously published species distribution map used in the threat classification in the IUCN Red List includes large areas of distribution in the Sichuan Basin plain, characterized by relatively low elevation and a high density of human disturbances, where no suitable takin habitat exists. Our analysis, based on readily available environmental data and a standard habitat suitability modeling approach, indicate that the CDR in Sichuan is substantially larger than its likely realized distribution(Figure 2). Our informed prediction of the total area of habitat available was only 19% of the area used to determine its threat classification, potentially vastly underestimating their extinction risk. Therefore, we suggest two steps to adjust Sichuan takin CDR and improve the accuracy of the IUCN Red List assessment. First, eliminate patch B and C where there is no effective habitat for takin. Second, shrink the east range of area A based on the boundary of these results and the known elevation lower limits (1,000m).
Our approach in this study was conservative. In reality, takin populations are sensitive to intense human disturbances (Zeng et al, 2008, Guan et al.,2015) and their populations are strongest within the nature reserve network and nearby forests that are protected by rangers from extensive human activities. This is supported by both the species distribution model results of this study, which indicated that more than 40% suitable habitat was located within PAs, and our previously published distribution, in which we found 77% of suitable takin habitat was located within 3km from the border of PAs in northern Minshan (Guan et al.,2015). It is likely that further species distribution models, with additional habitat disturbance variables, would indicate that the real world distribution of takins would be much smaller than current maps.
The IUCN Red List assessment is the most widely applied standard and reference for wildlife conservation used to determine priorities for conservation and ecological studies (Pimm et al., 2014). Thus, the accuracy of Red List assessments has global impact. The distribution of takin in our reassessment makes a clear case for the use of basic occurrence data to reduce inaccuracy, as about 40% of the CDR was outside of their possible distribution area. By contrast, giant panda distribution range in the same region is much more elaborate in shape and closer to their real world distribution (Tang et al., 2020), as the result of enormous monitoring and focal surveys (Zheng et al.,2012;Foretry Department of Sichuan Province,2015 ). Such condition demonstrate that the accuracy of estimats are highly varied among species, even those that are sympatric.
Species distributions are extremely important topics in both biology and ecology (Jetz & Guralnick, 2012; Pimm et al., 2014; Schluter& Pennell, 2017), since they evolve through both long-term evolutionary pressures and interactions with contemporary environmental and anthropogenic impacts. Thus, they are also a primary concern in wildlife conservation. For many common species on Red List, the occurrence data for distribution assessments and population estimates are still lacking (Roberts et al., 2016; Ocampo-Peñuela et al., 2016; Popov et al.,2017). To date, there are 17,878 species assessed by IUCN classified as “Data Deficient”, though comprising only 17.8% of all assessed species (IUCN 2020). As more research is done this percentage decreases, supporting more reliability in conservation assessments and more effective planning. We recognize that the data for species assessments often originate from widespread and long-term surveys, which are dependent on numerous factors, including the number of individuals participating in the research, support from pertinent stakeholders, and funding availability. However, as even the most conservative estimates indicate that the rate of extinction is 100 times higher than the normal background rate between the Earth’s six mass extinction events (Ceballos, et al., 2015). It is imperative that more targeted studies and surveys are completed to rapidly produce the critical data for conservation. Our results are likely true for numerous species, and there are significant opportunities for IUCN Red List species distribution estimates to be improved by including even basic biological limits and conservation dependencies (e.g. takin are not found within cities or other densely populated areas or below 1000m asl) into distribution maps (Sillero et al.,2014; Syfert et al.,2014; Ramesh et al.,2017;Gomes et al.,2018).
Biodiversity conservation has often been seen to conflict with economic development, lead to relatively limited conservation-related investment from governments, particularly those of developing countries. With the global economy growth and poverty reductions, long term monitoring and survey work in large areas become more affordable and feasible (Cordero et al., 2020); the body of related data is growing. For example, a recently deployed widespread infrared camera monitoring network in China has contributed national species distribution data (Li, 2020). However, the practical use of these data into species assessments and conservation actions remain to be seen. As data becomes increasingly available, it is absolutely essential that ecologists, biologist, conservation scientists and other organizations share data through transparent collaborations to improve our capacity to assess and protect wildlife.
Conclusion
By using the takin as a case study, we found significant disparities between their current published range in the IUCN Red List based on basic habitat requirements of the species. These differences can have substantial implications on the conservation of the species, including its threat classification, prioritization for funding and research, political and public attention, and more. Our findings related to the takin are likely exemplary of numerous species, even those not classified as “Data Deficient.” We strongly encourage an increased emphasis on widespread assessment of species ranges, even with only the most basic and intuitive data, to increase their accuracy and efficacy in conservation planning.
Acknowledgment: This work was funded by National Natural Science Foundation of China (31300319). We are grateful for the support from the Forestry Department of Sichuan Province, including data, and extend our thanks those who conducted field surveys and persistent monitoring in takin range for years, constructing the very foundation of our study.