Assessment of climate change impacts on one of the rarest apes on Earth, the Cao Vit Gibbon Nomascus nasutus

Abstract

The Cao Vit Gibbon (Nomascus nasutus) is a critically endangered species of gibbon that was historically wide-ranging but is now known to occupy only one forest patch that straddles the China-Vietnam border. While past and current threats to the species include poaching and habitat destruction, the potential effects of global climate change on this species and its current habitat are still poorly known. Species Distribution Modeling (SDM) is often used to predict the risk of potential species distribution shifts in response to climate change and inform conservation planning including restoration and reintroduction efforts. Here, we present optimally tuned SDMs to predict climatically suitable habitat for N. nasutus, projected under a range of future climate change scenarios. Our SDMs showed high predictive performance and successfully predicted the current known range, but also showed expected areas of overprediction to a much wider area that likely reflects the historical distribution of the Cao Vit Gibbon across southern China and northern Vietnam. SDMs that projected across a range of future scenarios estimated an overall loss in total area of climatically suitable habitat, with the average value of about -23,000 km 2 in 2041 -2060 period and about -25,000 km 2 in 2061 -2080 period, compared to Highlights• For species with a very small population such as the critically endangered Cao Vit Gibbon, climate change presents a potentially severe threat to its long-term conservation in synergy with other direct threats such as habitat loss and poaching.• Planning for habitat restoration and population re-establishment efforts for critically endangered species should take into consideration future climatic suitability.• Cross-border partnerships are essential for conservation management of critically endangered species under climate change.• Species distribution models for the critically endangered Cao Vit Gibbon suggest its current occupied area will remain climatically suitable into the future, and while the total area of climatically suitable habitat in the future is highly likely to decrease overall, we reveal potential sites for habitat restoration and population re-establishment.

Transboundary conservation hotspots in China and potential impacts of the belt and road initiative

“…Many transboundary species, including the Myanmar snub‐nosed monkey ( Rhinopithecus strykeri , <950 individuals in China and Myanmar, Yang, Tian, et al, 2018), the newly discovered skywalker hoolock gibbons ( Hoolock tianxing , <150 individuals in China, Zhang et al, 2020) and Cao‐vit gibbons ( Nomascus nasutus , 107–136 individuals in China and Vietnam, Ma et al, 2020) are endemic to this area and each has a tiny population. Without effective transboundary conservation, poaching and habitat loss and degradation will be difficult to regulate (Trinh‐Dinh et al, 2022; Wang et al, 2021). Also, the SW hotspot has insufficient PA coverage (12.2%) and low connectivity (ProtConn 1.68%), especially in China, Myanmar and India (Table 2).…”

Species distribution modeling to inform transboundary species conservation and management under climate change: promise and pitfalls

“…Machine-learning based SDMs are used for a wide variety of applications relevant to transboundary conservation efforts, including guiding field surveys to accelerate discovery of unknown range areas and species (e.g., Raxworthy et al 2003), predicting invasive species risk (e.g., Peterson et al 2008) or supporting conservation area priority-setting and reserve selection and related corridor networks (e.g., Senior et al 2019), and more (as reviewed in Urbina-Cardona et al 2019). Importantly in the context of this special issue, SDMs can identify the parts of a species' geographic range that are expected to be more susceptible to climate change (e.g., Blair et al 2022a, Trinh-Dinh et al 2022.…”

“…When used in combination with other information, accounting for bias and uncertainty, and trained well, SDMs have great promise to help conservation managers be forward-thinking about the possibility of endangered species moving out of their current distributions and to prepare for coordinated transboundary management, among other strategies. For example, in this issue several studies identify potential areas suitable for population re-establishment and community monitoring (Blair et al 2022a, Trinh-Dinh et al 2022, and for refugia for species (Nguyen, T.A. et al 2022, this issue).…”

Population Status and Conservation of the Largest Population of the Endangered François’ Langur (Trachypithecus francoisi) in Vietnam

“…However, due to different direct threats, including habitat loss and poaching, populations of many species, e.g., the Cao-vit Gibbon (Nomascus nasutus), Cat Ba langur, Delacour's langur, and Tonkin snub-nosed monkey, have been severely declining to lower than a few hundred individuals [6][7][8][9]. The existing threats coupling with the imminent impacts of climate change could bring the species to the brink of extinction [10][11][12][13]. As a result, Vietnam's primate fauna is considered the most threatened in the region with all but two species, i.e., the Assamese macaque (Macaca assamensis, listed as Near Threatened) and the rhesus macaque (M. mulatta, listed as Least Concern), classified as globally Vulnerable and above [14] (Figure 1).…”