Document: GIL-3-83-6

Modeling the management program of the Mountain Gazelle population in the Golan Heights, Israel.

BEN-NATAN, G.* ¹, I.TSURIM ¹, A.LEVY ¹, D.SALTZ ¹ and D.KAPLAN ²

Ben-Gurion University, Israel ¹
Israel Nature and National Parks Protection Authority, Jerusalem 95463 Israel ²

Abstract:
Since the implementation of the "Wild Animals Protection Law" in 1967, the population size of the mountain gazelles (Gazella gazella; BOVIDAE) in the Golan Heights of Israel, has grown from under 500 to over 5000 individuals in 1985. This created two major conservation and management problems: 1) Extensive damages to agriculture 2) The gazelles were suspected as a reservoir and source for the Foot and Mouth disease, and are held responsible for its eruption in northern Israel in 1985. Therefore a culling program was devised, based on the estimated carrying capacity of the Golan heights, and on the estimated population size in which disease eruption is limited. Hunting was to be intensive in the first two years and to be continued as moderate culling in subsequent years. In reality, hunting was continued, even though the desired limit has been reached. However, while another population (in Ramot-Yissakhar, where the same program was executed) remained stable around the desired level, the Golan Heights population continued to decline from unknown reasons, and is now ca. 0.4 of the desired population size. We have used a simulation model in order to explore the importance of several biological parameters and the consequences of various environmental scenarios, under the imposed hunting regime. The model used the estimated population size of 1985 as a starting point and deducted the number of individuals hunted each year according to age group. Results show that when specific age dependent mortality was added to the model (namely, an increase in yearlings mortality), the trajectory described by the model fitted nicely to the population estimates in the field. From the parameters incorporated into the model, their sensitivity, and the general fit to the field data, we offer several insights and make specific predictions as to this year population size. Our analyses suggest, that the population decline at present time does not stems from restrictions of field carrying capacity. However, the intensity of young mortality has shown a threshold, under which the population is driven to extinction and over which the population increases rapidly. These two insights suggest to us that special attention should be given to the younger age groups (newly born and yearlings) in order to prevent local extinction.

Keywords: Modeling; Ungulate; Conservation; Managment; Survival

This abstract is being presented at: 3:30 PM in session:
ANIMAL ECOLOGY