M.Sc Thesis

M.Sc StudentNezer Oded
SubjectHabitat Distribution Model for the Asiatic Wildass (Equus
Hemionus) and the Factors Influencing his
Distribution in Israel
DepartmentDepartment of Civil and Environmental Engineering
Supervisors PROF. Yohay Carmel
DR. Shirly Bar David


Identifying and understanding the factors that control species distribution is critical to the establishment of conservation and management strategies for both species and their habitats.

Habitat distribution models are basic and widely used tools for identifying essential habitats for species’ conservation.

Once distributed widely in west Asia and the Middle East, Equus hemionus has become extinct from these regions due to hunting and the destruction of its natural habitats. Between 1982-1993, Equus-hemionus was reintroduced in Israel. Today the species is distributed throughout the Negev desert, however, little is known about its habitat preferences and its degree of adaptation to different landscapes.

The goal of this research was to determine the habitat preferences of the wild ass and identify the factors that affect its distribution in both fine and coarse scales.

A comprehensive scat survey was conducted in 122 sites throughout the Negev. The sites were selected using a semi-systematic sampling scheme. In addition, a database of spatial layers of explanatory variables was constructed, including the following variables: distance to water sources, distance from reintroduced sites, climatic factors, topographic factors, woody vegetation cover and anthropogenic influence.

The spatial distribution of scat density data was analyzed using multivariate linear regression with the explanatory variables in order to identify the factors affecting the wild ass distribution at a coarse scale. G.P.S location coordinates of scat piles along with the spatial explanatory variables served as the basis for the construction of a MAXENT-type (presence-only) high resolution (10m) spatial probability model and to identify the factors affecting the wild ass distribution at a fine scale.

At the coarse scale-woody vegetation cover was found to be the best predictor of spatial distribution, followed by topographic elevation, distance from perennial water sources, and average annual precipitation. The combination of these factors accounted for >50% of the variance in the scats spatial distribution. At a fine spatial scale the most important factors were: percentage of woody vegetation (47.5%); slope inclination gradient (29.1%); daily temp in August (9.1%); and distance from permanent water sources (3.9%). We evaluated the model using in two independent methods and received good model performance.

The results of the models in both spatial scales indicate the importance of vegetation coverage, topography and water sources in the species’ habitats.

Our findings contribute to the understanding of E. hemionus habitat preferences and can serve as the basis for predicting the future range expansion of this species.