SDMs are used to generate habitat suitability maps, which are vital to developing a priority area or reserve in order to effectively conserve endangered species (Di Pasquale et al. 2020; Rather et al. 2020). This study was the first to look at both current and future potentially suitable habitats for C. simensis across the Ethiopian highlands, with a focus on the impacts of climate change on its habitat using the MaxEnt model. The results indicate that the predicted habitat suitability for the target species was done with a high degree of accuracy, with an AUC of 0.969 with standard deviation of 0.016. Comparably, Evangelista et al (2008) found an AUC value of 0.89 for Tragelaphus buxtoni in Bale mountain 0.902 for Capra walia in the Simen mountain, Ethiopia (Gebremedhin et al. 2021) and a predicted value of 0.913 for golden jackal in northeastern Italy (Torretta et al. 2020). These figures indicated for good accuracy in evaluating the success of a niche model (Swets1988; Elith et al. 2011).
Our findings showed that ten predictor variables were affected the predicted habitat suitability of C. simensis including the maximum temperature of the warmest month. Evidence shows that temperature is one of the most important predictors of future range expansion for species (Smeraldo et al. 2021). In contrast, precipitation in the wettest quarter have significantly influenced the habitat suitability and distribution of Colobus guereza gallarum in the eastern Ethiopian highlands (Kufa et al. 2022). Temperature and precipitation patterns, from monthly to seasonal, have a direct impact on species' biological behavior and physiology, as well as distribution, abundance, and interactions (Hirzel and Le Lay 2008; Walther et al. 2002). These variations in the contributions of bioclimatic variables on species distribution in different regions could be explained by the influence of agro-ecological variety around the world (Kufa et al. 2022). Climate change and anthropogenic activities have a major impact on the expected distribution, habitat connectivity, and genetic diversity of an endangered ape (Rhinopithecus bieti) (Zhao et al. 2019). Similarly, habitat fragmentation had a significant impact on predicted habitat suitability and distributions of wildlife (Guisan and Zimmermann 2000).
The present result showed that montane moorland had the highest HSI. Afro-alpine and Moorland have a high suitability for species (Randall et al. 2006). Similarly, alpine vegetation has been found to provide a better suitable habitat for Ethiopian wolf ( Marino 2003a). The broad evergreen (0.77 HSI), shrubland deciduous (0.67 HSI), and cropland (0.65 HSI) are also the most influential predictor variables for the predicted habitat suitability of C. simensis. Similarly, evergreen and deciduous forests are the most significant predictor variables for C. g. gallarum (Kufa et al. 2022). Furthermore, natural forest (Widyastuti et al. 2020) and good tree cover (Freirefilho and Palmeirim 2020) are predominant variables for the Hylobates moloch and Alouatta ululata, in Indonesia and in north-eastern Brazil, respectively. The vegetation integrated with density estimates of prey species' habitat connections has a significant impact on ecological niches (Tallents 2007). Among the slope categories, steep and very steep boosted habitat suitability for a targeted species. Although use all Afroalpine habitats, they prefer open areas with short herbaceous and grassland ecosystems where rodents are most plentiful, as well as flat or gently sloping slopes with deep soils and poor drainage locations (Marino & Sillero-Zubiri 2013). Similarly, Walia ibex has utilize the steepest slopes as highly suitable areas (Gebremedhin et al. 2021).
Our predicted model indicated the highly suitable habitats are very small, fragmented, and restricted to the isolated Afromontane Ethiopian highlands. New suitability regions, such as Melka Balo (West Harergahe), Addis Abba Zuria, and others, were revealed on the projected map, where there were highly fragmented and small areas. However, in comparison to the entire country, the overall area suitable for C. simensis is low. The suitable areas are much smaller than the total suitable areas of the Theropithecus gelada (Ahmed et al. 2022, under process). The future climate change in both global circulation models had a significant change in the predicted suitable habitat of a taxon. In contrast, there was a significant overall gain in suitable habitat for C. g. gallarum under future climate emission scenarios (Kufa et al. 2022). There is also evidence that suitable habitat for Walia ibex has notably increased in Simen mountain national parks under future climate change scenarios (Gebremedhin et al. 2021). However, in the BCC-CSM5 (SSP 2070 8.5), 25.18% of the area was lost from the highly suitable habitat. Significant differences in suitability indicate that climate change poses an unprecedented threat to global biodiversity by disrupting habitat distribution patterns (Sales et al. 2020). Historically, Ethiopian Wolf were found in eastern and southern Ethiopia (Hararghe and Sidamo) provinces, but now they are locally extinct (Yalden 1983; Marino 2003b). This might be due to climatic change and anthropogenic pressures or shifting in the geographic range. New strategies may be needed to avert biodiversity loss resulting from the effects of climate change across the globe (Lu et al. 2020); otherwise, such decreased changes may lead to the local extinction of a species (Preau et al. 2020).
Continuous climate change has a significant detrimental effect on the occurrence zone of this species, modified and newly added by this study, notably in the all-future scenarios. Eastern Ethiopia's highlands, Southeastern regions, central Ethiopia, northwestern region and Eastern Tigray all have newly discovered and extremely fragmented suitable habitat. However, these areas are vulnerable to fragmentation, deforestation, considerable logging of wood, particularly in the eastern forest region for timber production, grazing, and increased human settlements, which are all conservation concerns (Kufa et al. 2022). It is clear that, as a result of climate change, species' geographic distributions may be extended, altered, or shifted in the future (Sales et al. 2020). Ibex and blue sheep populations lose a substantial portion of their habitats as a result of changing climate conditions, particularly in the Himalayan and Hindu Kush regions (Ali et al. 2021).
Though a sympatric African wolves species have wide adapted environments (Gutema et al. 2019; Macdonald et al. 2019), the EWs have been limited to the Ethiopian highlands. It's important to note that anthropogenic activity expansions in Ethiopian wolf habitat are likely attracting African wolves, providing Ethiopian wolf with an impact area for inferred competition (Gutema et al. 2018). Understanding the effects of future climate change on species distribution would aid in the development of conservation policies aimed at reducing the danger of future biodiversity loss (Garcia et al. 2014; Kujala et al. 2013; Nazeri et al. 2014; Shrestha and Bawa 2014; Aryal et al. 2016). The wolf population is positively related to diurnal rodent density, and rodents account for 79.5% of wolf prey in the Afroalpine (Yihune and Bekele 2014). Effective conservation of the taxon should have included not only wolves but also their prey.
Overall, identifying data on a targeted species' geographical range of highly suitable habitat is critical for laying the plans for conservation efforts and formulating policies (Thorn et al. 2009; Aryal et al. 2016). In this study, the change in location of suitable habitats due to the warming climate over time may lead to a decrease in connectivity, resulting in the local extinction of species (Preau et al. 2018). This expected habitat suitability model helps with future conservation plan for endangered and declining species. The climatic conditions and topographical patterns of the research region contributed a lot in predicting the suitable habitats of C. simensis even though they have fragmented, as the existing models indicate. There is also a need for more data on the areas inhabited by a species within its distribution range, as well as connectivity across fragmented patches (Boitani et al. 2008). To be effective in the conservation of this endemic species in the Ethiopian highlands, other anthropogenic factors should be considered.