1. Introduction
In recent years, global warming has significantly impacted numerous vertebrate species, including mammals, leading to their rapid decline or even extinction within their ecological niches [
1,
2]. These ecological niches are crucial for species survival and their interactions with environmental conditions, promoting viable populations and their persistence over time [
3]. The rapid decline of these ecological niches is expected to worsen as the pace and magnitude of global environmental warming continue to accelerate [
4]. This is more concerning for mountainous and temperate regions because these areas are highly sensitive to temperature changes, which can lead to rapid and significant ecological disruptions as even small increases in temperature can cause accelerated snowmelt, shifts in vegetation zones, and habitat loss, creating more immediate and severe impacts compared to more stable lowland environments [
5,
6]. Mountain mammals cope with thermic stress and decreasing suitable areas by shifting to higher altitudes, altering their activity patterns, seeking cooler microhabitats, adjusting their diet, and modifying reproductive strategies, while conservation efforts focus on expanding protected areas and improving habitat management to support their adaptation [
7,
8]. Therefore, this situation is particularly pronounced in remote and highly elevated mountainous regions, such as the Himalayas and adjacent ranges in South Asia [
1]. The continental drift theory suggests that the Indian and Eurasian plates collided around 50 million years ago, forming the Himalayas, also known as “the abode of snow” in Sanskrit, and creating a complex geological wedge with three tectonic domains from north to south [
9,
10]. The Himalayan range is divided into three sections: the western, central, and eastern ranges, each home to unique flora and fauna, including many mountainous ungulates. Unfortunately, many of these species lack adaptive strategies to cope with new climatic conditions [
11,
12,
13]. The eastern Himalayan range, in particular, suffers from limited research and adaptive conservation strategies due to its remoteness, challenging terrain, and inadequate infrastructure. This leaves many species understudied, necessitating the identification of suitable areas where large ungulates with narrow niches can find refuge under future climatic conditions to improve conservation efforts [
14,
15]. This strategic approach is of utmost importance for the Red Goral (
Naemorhedus baileyi), a cliff-dwelling Bovidae species (order Artiodactyla) classified as “Vulnerable” by the IUCN Red List due to its small and declining population [
16]. Morphologically, this species is a vibrant foxy-red mammal characterized by its long, soft, shaggy hair, with a thin, dark stripe running along its back from head to tail [
17]. The legs of this species exhibit the same rich red hue as the rest of its body, while the undersides are a lighter buff color. The Red Goral has the most restricted range of all goral species, confined to the temperate mountains of northeast India (Arunachal Pradesh), northern Myanmar, and China (southeast Tibet and Yunnan). This is the only goral species in this range and inhabits higher elevations than most gorals, found between altitudes of 2000 and 4500 m [
16].
Since this species has an extremely restricted range and a very small population size, its vulnerability to climatic shifts and habitat alterations is markedly increased, making it particularly susceptible to changes in environmental conditions and disruptions to its habitat [
18]. Therefore, habitat mapping and modeling corridors across the species’ distribution are essential for prioritizing conservation strategies [
19]. These efforts will demonstrate the suitability and viability of habitat patches for wildlife occupancy and movement between them, thereby facilitating natural gene flow and enhancing long-term survival [
20,
21]. Furthermore, identifying the key factors driving shifts in species’ distribution ranges due to climatic changes is crucial, as understanding these drivers will offer insight into the environmental alterations that impact habitat preferences and movement patterns, ultimately guiding the development of effective conservation and management strategies [
22,
23].
In recent years, there have been significant advances and widespread adoption of species distribution models (SDMs) for assessing habitat suitability [
24,
25]. This methodology facilitates the mapping of species distribution patterns and the quantitative evaluation of various environmental factors [
25,
26,
27,
28]. Consequently, the ensemble model has emerged as a robust tool for estimating habitat suitability across different species [
29]. This approach integrates multiple modeling algorithms to predict species distributions across geographic areas, leveraging the strengths of various models to capture diverse aspects and underlying processes influencing distribution [
30]. The integrated approach combines various modeling methods, each capturing different aspects and underlying processes that influence species distribution. This strategy seeks to balance the strengths and limitations of individual models, leading to improved prediction accuracy and reliability. Furthermore, understanding the response of key driving variables to climate change is essential for identifying suitable habitats, which is critical for developing effective conservation strategies and landscape-level management plans [
31,
32]. Moreover, studying the IUCN extent is justified as it involves a systematic process that includes mapping and analyzing the geographical distribution of a species using occurrence records, adjusting for geographical barriers, and verifying with expert knowledge to accurately represent the species’ natural distribution for conservation planning and risk assessment.
Therefore, this study utilizes an ensemble approach in SDM within the IUCN range of the Red Goral, N. baileyi, to (i) determine the suitable extent under current and future climate change scenarios; (ii) analyze the patterns of habitat fragmentation resulting from climate change; (iii) identify biological corridors within the range; and (iv) assess the suitability and connectivity of transboundary protected areas (PAs). This study is vital for enhancing conservation efforts for this species that lacks extensive research and faces vulnerability in the ecological context. The identification of suitable habitats under current and future climate scenarios will reveal the areas in which this species can thrive within the IUCN extent and the habitat shifts with changing conditions to guide conservationists in India and adjoining countries. Moreover, understanding patterns of habitat fragmentation and connectivity will aid in safeguarding these corridors that will enable movement for this species and ensure transboundary migration and genetic connectivity within the known range. Furthermore, evaluating the suitability and connectivity of PAs will ensure coordinated conservation efforts across borders, creating an international network of safe havens and supporting broader conservation initiatives to save this threatened ungulate species in the wild.
4. Discussion
Recent research has highlighted troubling trends in the global decline of mammalian species and populations, underscoring the severity of the situation [
64]. This widespread decrease in mammalian diversity can largely be attributed to changes in land cover and environmental crises driven by climate change, particularly in South Asia [
65]. Although numerous studies have been conducted worldwide to address these issues in various mammalian species, this work stands out as the first comprehensive analysis of the distribution, habitat suitability, and connectivity of viable patches for the Red Goral. The intricate details provided by this study not only fill a critical gap in understanding this particular species but also offer valuable insights that could guide future conservation efforts.
The findings reveal deeply concerning trends for the Red Goral, as the model identified only 21,363 km
2, or a mere 13.01% of the total area, as suitable habitat within the IUCN extent under current conditions (
Figure 3,
Table S2). This limited, suitable habitat is alarming, as it leaves the species with very little space to thrive. Furthermore, this situation is compounded by the fact that only around 22.29% of this identified suitable habitat falls within the PAs, further constraining the species’ ability to survive in a protected landscape. The future projections paint an even grimmer picture, with a predicted decline of over 34% in suitable habitat extent. Given the restricted range of the species, this additional reduction due to climate change significantly worsens the situation. These findings are consistent with previous studies that concluded red gorals might face more severe challenges in the Tibetan Plateau adjoining the eastern Himalayas from the pronounced impacts of climate change [
66,
67]. Furthermore, the gorals are particularly vulnerable to habitat loss and environmental changes because of their limited movement range in restricted extent [
68]. The alarming results underscore the necessity of enhancing research efforts focused on habitat modeling and identifying key predictors for species conservation. This type of research is especially critical for lesser-known ungulate species with very restricted ranges, such as the Red Goral [
23]. Additionally, these research initiatives can provide valuable insights and inform conservation strategies to mitigate the adverse effects of habitat loss and climate change, ultimately aiding in the preservation of these vulnerable species.
Therefore, the present study identifies precipitation seasonality (bio_15) as the primary contributing predictor to the distribution of the Red Goral, accounting for 35.87% of the overall model (
Table 2). This bioclimatic variable is closely followed by elevation, which is the second highest contributor, aligning with the observation that the species is predominantly found in the high-altitude mountains of the eastern Himalayas [
16]. This finding corroborates previous studies conducted on various ungulate species, which have similarly highlighted the critical roles of precipitation and temperature as the top bioclimatic variables influencing their distribution [
1,
32]. Specifically, it was established that precipitation was the most influential variable in the distribution of ungulate species. This aligns with the results of the present study, where precipitation seasonality (bio_15) and precipitation of the coldest quarter (bio_19) are identified as significantly influential variables. However, the model in this study selected a different set of precipitation and temperature predictors compared to previous research, which could be attributed to the unique geographical context of the eastern Himalayas rather than the western ranges. Furthermore, elevation emerged as another key factor in predicting the habitat of the Red Goral, accounting for 33.69% of the overall model, suggesting that these animals may prefer higher-elevated temperate forests [
10,
69,
70]. Therefore, the temperate forest variable (euc_111) also emerged as one of the most significant predictors for this species, contributing 14.63% to the prediction of the model.
The implications of these findings are particularly critical in the context of climate change in the future, as the distribution of the Red Goral is projected to shift towards the northeastern direction, corroborating the previous studies [
20,
71]. This northward shift in the Eastern Himalayan and Tibetan regions is clearly exhibited in the present study, emphasizing the need for proactive conservation efforts. Moreover, as the climate continues to change, it will be essential to focus conservation strategies on PAs that are likely to experience these shifts. Furthermore, ensuring that these PAs are well-prepared to accommodate the changing distribution of the Red Goral will be crucial for the species’ long-term survival. The study identifies nine designated transboundary PAs within the IUCN range of the Red Goral, highlighting their crucial role in supporting the species’ survival over time (
Figure 3,
Figure 4 and
Figure 5). Among these, the DWLS in Arunachal Pradesh, India, is revealed as the PA with the largest extent of suitable habitat in the present scenario (
Table 3). Additionally, HkNP in Myanmar also possesses a significant area of suitable habitat. These two PAs maintain considerable suitable habitat patches in future projections despite suffering some losses due to climatic shifts. This trend can be attributed to the anticipated northeastern shift in the distribution of Red Goral caused by climate change aligning with the geographic locations of these PAs and mitigating their losses to some extent. Moreover, the TPRYPA in China is projected to experience significant habitat loss. It is important to note that this PA is extensive, and only a small portion of it falls within the IUCN range of the Red Goral, which may explain discrepancies between the suitable habitat extent and mean habitat suitability results. The mean habitat suitability averages the quality of various habitats within the studied area, reflecting the overall potential for the species to thrive based on different environmental factors [
72]. As a result, YRSWLS in India has the highest mean habitat suitability score (2.497) despite having a much smaller suitable extent (134 km
2) than the other areas, which may be attributed to its relatively smaller size. This difference highlights the importance of considering both suitable extent areas and mean habitat suitability to gain a comprehensive understanding of the landscapes. It is notable that DWLS is unique in ranking high in both suitable extent and mean habitat suitability, making it a priority conservation area for the Red Goral. However, the entire distribution within the PAs is projected to be affected by climatic shifts, leading to a decline in both suitable habitat extent and habitat suitability scores. This trend results in significant fragmentation, especially in PAs like YRSWLS and MNP, where future scenarios predict a dramatic decline of over 90% in suitable areas. Additionally, the threat of irreversible biodiversity decline is particularly severe in these landscapes, which are already fragmented due to ongoing habitat loss from development activities. These activities reduce patch sizes and increase distances between patches, disrupting connectivity and exacerbating edge effects. The increased habitat fragmentation is linked to higher rates of species decline due to additional habitat loss [
73]. The present study corroborates these findings, demonstrating that extensive reductions in suitable habitat have led to significant spatial alterations and fragmentation, adversely affecting the Red Goral and other ungulate species.
The distribution extent of the Red Goral has undergone extensive fragmentation due to climatic shifts (
Table 5). This severe fragmentation of viable patches is evidenced by a notable increase in the NP metric by 26.39% in SSP245 (2041–2060) and 21.38% in SSP585 (2041–2060) when compared to the present scenario. These increases reflect a significant disruption in the continuity of the species’ habitat, indicating that climate change is causing the habitat to break apart into smaller, more isolated patches. However, this rate of increase in fragmentation reduces to 17.75% in SSP245 (2061–2080) and 13.55% in SSP585 (2061–2080). This deceleration in the rate of fragmentation may be attributed to the complete loss of some viable patches, which reduces the total number of fragments, indicating a critical threshold of habitat destruction. The increase in NP is also linked to the disintegration of suitable habitats, which has led to higher PD and ED in future scenarios while decreasing the LPI. This indicates that the fragmented patches have decreased in size and become more restricted for the species. Furthermore, the decrease in AI exacerbates the situation, as it signifies that these small, disintegrated patches will be far from each other, thus hindering the movement of the species. This fragmentation is particularly concerning because it could restrict gene flow among different populations of the Red Goral, potentially increasing inbreeding rates as these isolated patches are less likely to support viable populations over the long term [
19,
74]. Therefore, the identification and protection of corridor connectivity among fragmented habitats and PAs are crucial for the conservation of this species, as ensuring such connectivity will help maintain genetic diversity and facilitate the natural movement of the species, mitigating some of the adverse effects of habitat fragmentation induced by climate change.
The study assessed the corridors among the PAs within the Red Goral’s IUCN extent, identifying eight significant connectivity pathways (
Table 6). It revealed that the highest mean connectivity (0.0583) was found between DWLS and MWLS in the present scenario, followed closely by the corridor between MNP and DWLS, with a mean connectivity of 0.0538. Conversely, the lowest connectivity was observed between KWLS and NNP, with a mean suitability score of 0.0172. This is particularly intriguing given their close proximity, highlighting the necessity of landscape-level connectivity. Furthermore, important transboundary corridors, such as the one between HkNP and the TPRYPA, with a mean connectivity score of 0.0493, and the corridor between NNP and HpWLS, with a mean connectivity score of 0.0332, were identified, which necessitates transboundary cooperation and collaboration. However, future scenarios project a decline in crucial corridors due to climatic shifts in the landscape level for this species. Notably, a significant decrease of over 25% in mean connectivity is anticipated between YRSWLS and MNP, whereas the corridor between HkNP and TPRYPA is projected to experience the least decline in mean connectivity, up to 1%. This minimal decline witnessed between HkNP and TPRYPA is likely due to their close proximity, underscoring the importance of maintaining continuous transboundary landscapes. The findings underscore the paramount importance of implementing conservation strategies to maintain and augment connectivity between the PAs to ensure the long-term viability of the Red Goral and other species that are dependent on these temperate mountain habitats.
Thus, the PAs identified by this study require enhanced protection through implementation by governmental agencies; specifically, DWLS and HkNP, having the highest suitable extent, need immediate attention for conservation efforts. Additionally, considering the current sociopolitical situation in Myanmar, wildlife conservation efforts are severely jeopardized [
75]. As a result, the study strongly urges international communities to support conservation efforts in these regions by providing aid to indigenous people and non-governmental organizations. In the Indian context, the construction of new hydropower dams in Arunachal Pradesh, particularly in Dibang Valley, has led to the clearing of many hectares of forest land. The study suggests conducting impartial environmental impact assessments (EIAs) before initiating any construction and insists that construction agencies adhere to EIA regulations while supporting local conservation efforts. Furthermore, traditional practices like trophy hunting and bushmeat hunting, embedded in tribal cultures due to historically high forest cover and low human presence, must be addressed. The recent development in these areas calls for awareness programs to reduce hunting practices and encourage engagement in conservation work supported by the growing tourism industry. Moreover, the TPRYPA in China requires a landscape-level assessment to identify habitats for this species that are not included in the IUCN extent. Furthermore, it is crucial to monitor and prevent the trade of body parts of Red Goral and other ungulates for medicine in the international market through these significant wildlife trafficking routes. Moreover, it is necessary to encourage the establishment of more captive breeding facilities for both breeding and research, especially since there is currently only one such facility at the Shanghai Zoo in China [
76]. In order to effectively safeguard transboundary corridors, it is essential to maintain their continuity. When disruptions occur, it is important to implement measures, such as constructing underpasses or overpasses, to ensure better habitat connectivity. Achieving this goal requires collaboration and cooperation among the three countries involved. Moreover, forming community reserves with support from both international and national agencies is necessary for the long-term preservation of these vital corridors. Furthermore, a reassessment by the IUCN is also needed, potentially considering the species under the “Endangered” category, as this reclassification would help enhance protection and attention towards the species, which occupies a very restricted range and is significantly affected by climate change. Therefore, implementing these strategic measures will substantially enhance the conservation efforts for the Red Goral and other ungulate species.