Reptiles have a crucial part in maintaining global biodiversity and the functioning of dynamic ecosystems, owing to their ecological roles and functions. Nevertheless, these organisms are susceptible to human-induced disruptions and the deterioration of their habitats, leading to their categorization as the third most endangered group of vertebrates on a global scale. Understanding the spatial distribution of reptiles is crucial due to their often specific habitat needs and limited vagility. Morgan’s black cobra (Walterinnesia morgani) is a secretive venomous snake species that has thus far received little attention in Iranian scientific literature. The aim of the present study was to determine the existing distribution pattern of the cobra and to speculate on how climatic changes might affect it. Maximum entropy modeling was used to examine a dataset consisting of 16 occurrence records gleaned from field observations and the literature. The niche of the species was predicted using current and future climate change forecasts and bioclimatic and topographical characteristics. The models predicted a future reduction in the wide distribution region of W. morgani in southern and western Iran. It was discovered that climatic factors like temperature range, precipitation dynamics, and river proximity all played a key role in shaping the pattern of distribution. The predicted suitable areas for W. morgani were dependent on water sources; however, future scenarios showed a decline in suitable habitats. This study underscores the importance of conservation efforts in light of the potential implications of climate change on this species. To further understand the range shifts and adaptive strategies of the species, further study of its ecology and dispersal dynamics is required.

ecological niche, MaxEnt, Morgan’s black cobra, precipitation, topography

Reptiles, although they account for one-third of global terrestrial vertebrate diversity, have lagged behind other groups, such as birds and mammals, in terms of ecological studies (Biber et al. 2023). Due to the fact that reptiles are typically characterized by specific habitat needs and limited vagility (Guedes et al. 2018), understanding their spatial distribution is crucial. In this regard, revealing species distribution patterns improves our knowledge of the relationship between landscape and species. Climatic oscillations, like topographic and vegetation cover patterns, have contributed to the establishment of the distribution of species in different biomes (Bobrowski et al. 2018; Şahin et al. 2022a).

Although reptile species are widely distributed throughout the world, they are at risk of extinction due to habitat loss and degradation, pollution, invasive species, diseases, and climate change (Gibbons et al. 2000). Anthropogenic impacts–not only habitat use but also misinformation about their venomosity–have disproportionately threatened snake species (Saha et al. 2018). Therefore, evaluating the conservation status of these quite secretive organisms and determining their distribution patterns are important.

The herpetofauna of Iran comprises 81 species of snakes belonging to 34 genera and 7 Families (Rajabizadeh 2018). Family Elapidae, including Elapinae (3 genera, 3 species) and Hydrophiinae (1 genus, 10 species), is more diverse than Viperidae, including Crotalinae (1 genus, 1 species) and Viperinae (7 genera, 10 species) (Safaei-Mahroo et al. 2015; Rajabizadeh 2018). Despite increasing efforts to determine herpetofaunal distributions in Iran (Hosseinian Yousefkhani 2019; Vaissi 2021a, b, 2022), snake species remain understudied (Hosseinzadeh et al. 2017; Moradi et al. 2021).

The genus Walterinnesia Lataste, 1887 has two species known commonly as desert black snakes or black desert cobras including the type species Walterinnesia aegyptia Lataste, 1887 and Walterinnesia morgani (Mocquard, 1905) (Fig. 1). Both species occur only in the Middle East. The type locality of W. morgani is Khuzestan Province, southwestern Iran (Uetz et al. 2023). Populations of the species in Iran were previously considered as W. aegyptia by Farzanpay (1989), Latifi (1985, 1991, 2000), and Leviton et al. (1992). Nilson and Rastegar-Pouyani (2007), based on the lower scale row counts around the neck and a banded juvenile pattern (Fig. 2), recognized the eastern populations of the genus (from Turkey and Saudi Arabia to Iran) as W. morgani; however, Rajabizadeh (2018) considered the Iranian populations of the genus as Walterinnesia aegyptia morgani.

Figure 1. 

Occurrence records of W. morgani in Iran.

Figure 2. 

Recent historical (1981–2010) habitat suitability of W. morgani in Iran (warmer colors refer to high suitability level).

Walterinnesia morgani, Morgan’s black cobra or black desert cobra, is a venomous snake species that inhabits the Arabian Peninsula (Kuwait and Saudi Arabia), the extreme south of Turkey, Syria, and the majority of Iraq, as well as western and southern Iran (Ilam, Kermanshah, Khuzestan, Bushehr, Fars, and Hormozgan Provinces) (Joger 1984; Gasperetti 1988; Latifi 2000; Uğurtaş et al. 2001; Sindaco et al. 2006; Safaei-Mahroo et al. 2015). In a specific concept, the Zagros Mountains display a wide biodiversity pattern, as well as the Central Iranian Plateau and the northern Persian Gulf, in one of the well-known biodiversity hotspots (Irano-Anatolian Biodiversity Hotspot) in the Palearctic Realm (Gholamifard 2011; Mittermeier et al. 2011). Walterinnesia morgani is one of the representative charismatic species of this region, where its shiny black color draws attention and, as most of the sightings of this species lead to its death, is very important from the aspect of conservation.

Black desert cobras display nocturnal activity patterns (Uğurtaş et al. 2001). During the hottest parts of the day, they seek refuge in burrows or beneath rocks. The seasonal activity of desert cobras may be influenced by local climate conditions (Baran et al. 2006). In some regions, for instance, they may be less active during the hottest period of summer and more active during the cooler months (Baran et al. 2021). Nonetheless, they are capable of being active even in extreme temperatures and are acclimated to harsh desert environments (Baran et al. 2021).

In spite of the known distribution of Morgan’s black cobra, W. morgani, (IUCN status is Least Concern (LC)) in the Central and Southern Zagros Mountains, and its medical importance (Abid et al. 2020), the national literature on the species is scarce. The main reason for this is probably the difficulty of studying this mysterious and nocturnally active venomous snake. Therefore, the aim of this study was to reveal the current potential distribution pattern and speculate on the effects of climate oscillations on the potential distribution pattern of the black desert cobra in Iran.

The regions anticipated to be suitable for W. morgani exhibited a significant area under the curve (AUC) value of 0.955±0.014. Furthermore, the recent historical and future bioclimatic predictions (2071–2100) under the SSP126 and SSP585 scenarios had the lowest values for Akaike Information Criterion corrected (AICc) and the delta AICc at 0.169 and 0, respectively. (Figs 2, 3A–J; Table 2).

Figure 3. 

Future habitat suitability (2071–2100) of W. morgani in Iran based on A. GFDL-ESM4 under optimistic scenario (ssp 126); B. GFDL-ESM4 under pessimistic scenario (ssp 585); C. IPSL-CM6A-LR under optimistic scenario (ssp 126); D. IPSL-CM6A-LR under pessimistic scenario (ssp 585); E. MPI-ESM1-2- HR under optimistic scenario (ssp 126); F. MPI-ESM1-2- HR under pessimistic scenario (ssp 585); G. MRI-ESM2-0 under optimistic scenario (ssp 126); H. MRI-ESM2-0 under pessimistic scenario (ssp 585); I. UKESM1- 0-LL under optimistic scenario (ssp 126); J. UKESM1- 0-LL under pessimistic scenario (ssp 585) (warmer colors refer to high suitability level).

The fact that the AUC data were very close to 1 showed that the potential distribution area revealed by the locality data obtained from the distribution area of the desert cobra displayed a much better performance than a random prediction. For W. morgani, 1054 statistically significant models that had different regularization multipliers and feature classes were evaluated. Linear, quadratic and product (LQP) features along with a regularization multiplier of 0.8, and with the lowest delta AICc, was the best model. The most important variables were d_river (31.9%), Bio_9 (27.7%) and Bio_15 (14.7%), respectively.

According to the analysis, the potential distribution area of W. morgani covers a water source-dependent pattern in western Iran. Additionally, as can be seen in future climatic conditions, the potential distribution range would be narrower than under recent historical conditions. Habitat loss is expected in each future climatic scenario, but its level varies depending on the ssp level (Table 3). For instance, scenarios in ssp 126 level forecast the species range change percentile to be between -9.814 and -18.028%, however, the ssp 585 scenarios may result in a much greater loss of between 49.337% and 71.262% of the species’ suitable habitats in the distribution range (Suppl. material 4: fig. S1A–J; Table 3). As a result of all these scenarios, it is expected that the possible distribution of W. morgani will contract in southwestern Iran in the future.

Numerous biotic and abiotic factors have significant impacts on the distribution of species (Pearson et al. 2007). To understand the responses of W. morgani to climatic oscillations during recent history and under future possible scenarios, we employed ENM as a useful analytical instrument to assess the range of the species. Climate changes affect all aspects of biodiversity, from organisms (organismal diversity) to biomes (ecological diversity) (Gaston and Spicer 2004), and pose a significant threat to the integrity of ecosystems (Bellard et al. 2012). Additionally, it is speculated that vertebrate species will face serious problems of adaptation related to alterations in their climatic niches in the near future (Quintero and Wiens 2013). It should be noted that the distribution of reptiles can be significantly affected by direct and/or indirect anthropogenic activities, such as human population size and human-driven climatic changes (Bickford et al. 2010).

Based on these results, most of the suitable predicted areas were slightly wider than the present potential distribution of W. morgani. This might be the possible effect of “d_river” as one of the highest contributors to shape the distribution pattern via the water requirement of the species. Additionally, daily and annual temperature cycles have also contributed to the potential distribution pattern as well as the seasonal factors, especially the driest seasonal precipitation dynamics. This overall bioclimatic and topographic pattern is observed in many herptile species in and nearby the study area (Naumov et al. 2020; Kurnaz and Eroğlu 2021; Şahin et al. 2022a, b; Vaissi 2022; Kurnaz 2023).

On the other hand, our results show that there will be a future decrease in suitable habitats for W. morgani, but the level of the decreasing trend varies depending on the SSP levels and different future scenario sets (Suppl. material 4: fig. S1A–J; Table 3). This trend is compatible with many ecological niche modeling studies that have been applied to herptiles in the study area and nearby regions (Kurnaz and Şahin 2021; Bozkurt 2022). Additionally, this contraction pattern has also been predicted for future distribution trends in many lizard species (Vaissi 2022). Nonetheless, the genus Lacerta and two leopard geckos exhibit the opposite trend in the Anatolian Peninsula and Iran, respectively (Hosseinian Yousefkhani and Nabizadeh 2022; Gül et al. 2023).

When compared to other large vertebrate groups, the ability of reptiles to migrate is quite restricted (Hickling et al. 2006). Moreover, our knowledge about the ecology and dispersal dynamics of W. morgani has received little or no attention. Based on Figs 2, 3, the current research assumed an infinite capacity for dispersal across species and made predictions about its range changes through 2100. Despite contractions and expansions, the potential distribution range of the species under each ssp126 scenario remains less changed (Fig. 3A, C, E, G, I; Table 3); however, under ssp585 scenarios, the species will be contract in southwestern Iran (Fig. 3B, D, F, H, J; Table 3). In the pessimistic scenario (ssp585) for the IPSL-CM6A-LR climate projection, in particular, it is expected that there would be 71.26% habitat loss with only 0.51% habitat gain and as a result, there would be a 70.74% negative range change (Suppl. material 4: fig. S1D; Table 3). Additional factors, such as geographic barriers, may influence the migration rate of a species (Morena-Rueda et al. 2012). In our case, distance to the river and elevation parameters, as topographic variables, make significant contributions to the species distribution. Even though the Zagros Mountains can be assessed as a remarkable geographic barrier, the main limitation factor is the “distance to the rivers” for W. morgani. Because it seems that the cobra tends not to occur very distant from water resources. Moreover, even though the potential distribution map displays suitable habitats in central or eastern regions of Iran, it should be noted that this could be the consequence of bioclimatic and topographic similarities in distinct areas that the species is biogeographically incapable of inhabiting. A similar pattern to ours was observed in several studies which evaluate narrower regions (Heidari 2021; Bozkurt 2022; Şahin 2022b).

On the other hand, the model algorithm that was used in this study did not take into account some parameters, such as parasitism, disease, habitat loss, and fragmentation that might affect the realistic distribution of the species (Todd et al. 2010). In the meantime, a recent study that focused on snake bite risk in Iran showed that the northern and western parts of Iran would have greater risk than the rest of the country (Yousefi et al. 2023). However, our results pointed out that southwestern Iran could be a potentially suitable region for Morgan’s black cobra. No common potential distribution model was reported for W. morgani, neither country-based nor across-range, by including up-to-date topographic variables. Thus, our results suggest that W. morgani should be monitored in the near future, with more occurrence records collected in order to better understand its distribution and to increase awareness of human-cobra conflict as a result of anthropogenic activities. To conclude, it is desirable to predict the potential distribution of this species in Iran from the aspect of medical treatment of possible bites of the species and to prepare its antivenom.

A. Gholamifard and M.K. Şahin conceived the study. A. Gholamifard collected the field data and documentation. M.K. Şahin carried out the sampling design, statistical analysis and performed modeling. A. Gholamifard and M.K. Şahin contributed equally to writing the manuscript.

We thank Dr. Erica DeMilio for the proof reading and the respected anonymous reviewers and Editor Dr. Yurii Kornilev for improving the manuscript. We are grateful to Professor Aaron M. Bauer for editing the final version of this manuscript.