Will cinereous vulture (<i>Aegypius monachus</i> L.) become extinct in the forests of Türkiye in the future?

Türkiye shelters different habitats for bird species thanks to its location and geographical features (Karakaş, 2010; Kirwan et al., 2010). In other words, two of the four important migration routes in the Western Palearctic Region pass through Türkiye (Bilgin et al., 2016), which has very favourable ecological conditions for birds (Leshem and Yom-Tov 1998). Therefore, Türkiye has a rich ornithological fauna in terms of bird diversity and richness (Özay and Özkazanç, 2022). Türkiye hosts 491 bird species in total, 452 of which have been documented and 39 of which have not been seen for a long time, but their existence has been recorded (Dizdaroğlu, 2015; Elvan et al., 2022). Some of these include cinereous vulture ( Aegypius monachus) and imperial eagle (Aquila heliaca), which are among the world’s rarest vertebrate species (Collar et al., 1994; Donázar et al., 2002; Demerdzhiev et al., 2011). Furthermore, the fact that four vulture species belonging to the Accipitridae family have been found, namely bearded vulture ( Gypaetus barbatus), Egyptian vulture ( Neophron percnopterus), griffon vulture ( Gyps fulvus) and cinereous vulture ( Aegypius monachus), their distribution in Türkiye supports the indicator of bird species diversity and richness (Göktürk et al., 2008; Doğa, 2015; Doğa, 2021).

Cinereous vulture, which has the bulkiest body among the vulture species belonging to the Accipitridae family, is known to be among the largest bird of prey species in Europe (Ogada et al., 2012; Van Dooren, 2012). Although it has a bulky body, cinereous vulture can fly or glide silently in the air with its wide and long wings (Dunne and Karlson, 2017). Like all carrion eaters, they also feed on the carcasses of dead animals, snatch the prey of other predators and the like (García-Barón et al., 2018). In addition, cinereous vultures have an important ecological role since they are birds that can tear the skin of carrion, thanks to their strong and thick beaks (Ferguson-Lees et al., 2001; Chander, 2013). Thanks to the durable structure of their beaks, they can make their nesting sites both on trees and in rocky areas. Nesting sites in rocky areas can usually be found in Asia. In Europe, it has been recorded that the species prefers tree species such as juniper and oak (Reading et al., 2005; Moreno-Opo et al., 2012). In Türkiye, black pine ( Pinus nigra), and rarely other species from the Pinaceae family and oak species, may be used as nesting sites (Yamaç and Bilgin 2012).

However, adverse effects such as developing industry, increasing population rate and climate change brought about by advancing technology in the 19^th century have endangered some bird species (Carey, 2009; Upadhyay, 2020). This situation can be explained by the fact that in the last hundred years, the habitats of approximately 200 bird species in the world have been fragmented, shrunk, and even faced with the danger of extinction (Tabur and Ayvaz, 2010). These negative effects are still increasing even at the beginning of the 21^st century. For example, the habitats and distribution of cinereous vulture, which is thought to be around 50-100 pairs in Türkiye, has been adversely affected (Özçelik, 2009). This species, which has become extinct in countries such as Cyprus, Italy, Moldova, Romania, and Slovenia, is being rereleased into nature in France (Kirazli, 2013) in order to maintain its existence within the country.

The habitat preference and distribution of cinereous vulture has changed regarding the geography and landform where it is distributed (Gavashelishvili et al., 2012; Guerrero-Casado et al., 2013). In general, the regions with continental climate in the West Palearctic region are suitable habitats (Arslan and Kirazli, 2022). It shows a potential distribution from the temperate zone to the boreal zone vertically. In these regions it prefers high hillsides, upper slopes containing clearings and old trees as nesting sites. However, cinereous vulture does not prefer seacoasts, wetlands, and closed basins which are extremely preferred by humans as habitats (Carrete and Donázar, 2005). It also does not prefer areas where there are no suitable nesting trees or cliffs, and where harsh climatic conditions prevail. Therefore, changing climatic conditions pose a threat to the cinereous vulture and its potential distribution, which is also the case with other wild animals (Cramp and Simmons, 1980; Mert et al., 2016; Suel et al., 2018; Kıraç and Mert, 2019; Özdemir et al., 2020; Kıraç, 2021; Kıraç et al., 2022).

Different numerical and model-based methods, such as generalized additive model (GAM) or random forest (RF), may be used to perform endangered wild animal habitat suitability modelling and mapping (Hastie and Tibshirani, 1990; Miller, 2010; Rigatti, 2017). One such method is the maximum entropy (MaxEnt) software, which is a probability calculation method. In habitat suitability modelling and mapping studies of wildlife and bird species, the models produced by MaxEnt software provide more reliable and accurate results than other methods (Phillips et al., 2006). MaxEnt software comes to the fore for the protection, development, and sustainability of habitats when past, present and future climate models are considered, with minimal existing data on the target species that are endangered or at risk of extinction (Elith et al., 2011).

Global climate models make predictions for the future with the help of statistical analyses (Winsberg, 2012), considering current climatic conditions. Evaluating these models and obtaining the results covers a long and complex process. However, it has been stated that determining appropriate habitats for the target species using future climate scenarios is the most effective for taking protection measures (Hartmann, 2015; Pottier et al., 2017). In summary, while there are many global climate scenarios that may display an impact on birds, in general, Chelsa V2.1 climate scenarios are preferred (Ramesh et al., 2022).

This study aimed to reveal the current and future habitat suitability maps of the endangered cinereous vulture, which is distributed in Türkiye. For this purpose, Chelsa climate scenarios (IPSL-CM6A-LR SSP126-SSP370-SSP585) were

used for current (2010) and future (2100) modelling and mapping projections of cinereous vulture. As a result, areas that must be protected for the protection, development and sustainability of the cinereous vulture were determined.

MATERIALS AND METHODS

In this study, habitat suitability modelling and mapping of the cinereous vulture distributed in Türkiye was created. In addition, suitable habitats were mapped with Chelsa climate scenarios for the future, which demonstrated significant changes that have vital effects on the potential distribution of wild animal species. This mapping process demonstrates the importance of climate envelope models to obtain a representative understanding of long-term cinereous vulture habitat preference (Gavashelishvili, 2012). Therefore, it is very important to integrate climate change into numerical and model-based methods compared to old classical methods in wild animal habitat preferences (LeDee et al., 2021).

Table 4. Cinereous vulture habitat suitability modelling rate

Tablica 4. Stopa modeliranja prikladnosti staništa crnog strvinara

MaxEnt method was preferred due to various reasons. This is because MaxEnt method 1) gives the most accurate and reliable results with the least amount of data, 2) provides the opportunity to work with both categorical and continuous data, and 3) demonstrates the effects of climate, vegetation, and environmental effects (Phillips et al., 2004; Elith and Leathwick, 2009; Elith et al., 2011). According to model results, it was determined that there was no significant deviation in the average deficiency curve graph of cinereous vulture habitat suitability model. AUC values revealed that the selected replication was in the reliable and good model category (Baldwin, 2009). The standard deviation of the model was determined to be 0.031 and the variables contributing to the model were precipitation of seasonality, bedrock, isothermality and landform classification.

When the seasonality of precipitation is evaluated, which contributes most to the model created by the MaxEnt method, the importance of the amount of precipitation in taking off from the areas where cinereous vulture shelters and flying in the air is emphasized (Hiraldo and Donázar, 1990; Moreno-Opo et al., 2010). It has been determined that in the areas which receive heavy and long-term precipitation, the flying activity of cinereous vulture decreases and is practically almost zero (McGrady and Gavashelishvili, 2006; Morán-López et al., 2006). In addition, a study in the Sündiken mountains revealed that there are differences in the behaviour of cinereous vultures in December, which is the month with the heaviest precipitation in the area (Kirazli, 2015). This difference supports the great importance of the amount of seasonal precipitation for cinereous vulture. Finally, although the low reproductive success of cinereous vulture is generally thought to be caused by humans, excessive precipitation can negatively affect the reproductive success as well (Gavashelishvili et al., 2006; Gavashelishvili et al., 2012). Therefore, whether precipitation seasonality is too high or low affects the distribution, habitat preference and foraging activity of cinereous vulture.

When the bedrock graph is examined, unseparated volcanic rocks, pyroclastic rocks and evaporite sedimentary rocks show a positive relationship on the species distribution. Unseparated volcanic rocks generally have different degrees of weathering at different temperatures or cooling. They have cracks in their structure due to their ability to decompose upon heating or cooling. Pyroclastic rocks refer to all the fragments thrown out of the vents by the eruption of a volcanic mountain structure. Evaporite sedimentary rocks are generally formed by the evaporation of sea and lake water and are common in arid climate zones. Studies on cinereous vulture have found that they generally build their nests in cracked rocky areas in arid regions. It has also been stated that the species prefers trees and crump rocks in the high parts of the mountains as nesting areas (Cramp and Simmons 1980, Zhatkanbayev, 2011; Campbell, 2015). Even though some studies explain bedrock type choice, no study on bedrock characteristics that could have an impact on the habitat preference of cinereous vulture could be found. However, according to the bedrock map presented, bedrock areas in habitat preference are generally of great importance in nesting area preference. Therefore, the bedrock variable results presented are compatible with the literature.

The isothermality variable that contributes to the model emerges by dividing the difference between daily evening temperature and daytime temperature by the difference between annual evening temperature and daytime temperature (Karger et al., 2017). The study revealed that daily and annual temperature is important in the distribution of cinereous vulture. In literature analysis, it was found that this species prefers nesting areas where there is a warm air flow and there are no climatic conditions such as extreme heat or extreme cold (Morán-López et al., 2006). In addition, it was stated that daytime temperature is more important than night temperature in determining the seasonal movements of cinereous vulture. Also, it was revealed that cinereous vultures shelter at higher latitudes and altitudes (i.e., where the air is relatively cooler) during high daytime temperatures (Tarkhnishvili et al., 2012). Considering different climate warming scenarios (IPCC 2007), which assume that surface temperature will increase by 1.4–5.4°C over the next 100 years, they predicted that the distribution of cinereous vulture will move to higher latitudes and altitudes, especially in summer. More specifically, under these scenarios that predict climate warming, temperatures will increase, and precipitation will remain unchanged. It has been determined that the vegetation density within the area will decrease significantly according to NDVI (Normalized difference vegetation index) and there will be a change in species habitats (Gavashelishvili et al., 2012) As a result, as stated in literature, daily and annual temperature changes will have influence on cinereous vultures, and the increase in temperatures will cause the shrinkage or fragmentation of their habitats.

Landform classification that contributes the least to the model shows that canyons, upper slopes, upland drainages, and headwaters in the study area have a positive relationship in the species distribution. In this context, cinereous vulture prefers upper slopes rather than mountain peaks to dominate the area. Another reason why it prefers the upper slopes is to protect itself from predatory species on the mountain peaks or to easily reach its habitats (Moreno-Opo et al., 2013). In addition, it was revealed that it feeds by throwing the animals it hunts down from mountain structures such as canyons to meet its nutritional needs. Generally, upland drainages and headwaters with puddles that have lost their flow rate are described as areas preferred by the cinereous vulture in extreme and high temperatures (Yamaç and Bilgin, 2012; Erdoğdu, 2014; Chung et al., 2015; Kirazli, 2016; Yamaç et al., 2019). In conclusion, it was determined that the cinereous vulture prefers canyons, upper slopes, and dry streams where it can use the air flow more easily, instead of mountain peaks and flat areas, to feed, shelter, protect and survive.

In short, precipitation seasonality, bedrock, isothermality and landform classification results for the habitat suitability mapping of cinereous vulture are compatible with the literature. Climate variables such as precipitation seasonality or isothermality will affect cinereous vulture’s nutrition, shelter, or habitat preference. Changing precipitation seasonality within the study area will cause the species to leave the areas where they shelter and change their habitat preference. At the same time, the change in temperature will have an influence on the distribution of cinereous vulture, which has a large body, and whose body temperature will increase and cause a change in the food chain. Since its habitat preference, which has a wide distribution area, is sensitive to seasonal precipitation and isothermality, these factors will limit the current and future distribution of the species. If the increase in seasonal precipitation and isothermality continues due to changing climatic conditions, the species will face extinction in the year 2100 according to the SSP 585 scenario.

CONCLUSIONS

This study is the first numerical and model habitat suitability mapping of the cinereous vulture in Türkiye under climate change. In this study, areas that need to be protected for the cinereous vulture to survive the changing climate conditions and for the sustainable management of its generation were determined. Climatic and environmental factors can be used for vulture species distribution modelling or habitat suitability maps. The habitat suitability maps of cinereous vulture have the potential for guiding managers when undertaking forest and agricultural management practices and determining the initiatives for biodiversity conservation. In addition, the habitat suitability mapping of the cinereous vulture under changing climatic conditions will help to obtain information on how and in what way it will be protected. Finally, this study will contribute to researchers who will investigate the cinereous vultureclimate change relationship.

LITERATURE