برآورد فراوانی و ارزیابی نیازهای زیستگاهی گورخر ایرانی در پارک ملی قطرویه

Persian wild ass, Equus hemionus onager, is a rare subspecies of Asiatic wild ass endemic to Iran, which was historically widespread in arid and semi-arid steppes of central and southeastern Iran. Today only two natural populations have remained. This subspecies is listed as Critically Endangered in the Red List of the International :::union::: for the Conservation of Nature and Natural Resources. Knowledge on habitat use and population densities of this taxon is necessary for its successful conservation. We studied population density and habitat selection by Persian wild ass in Qatruiyeh National Park (QNP). Seasonal habitat use by onagers was studied using clearance transects and standing crop pellet group counts. Line transect distance sampling was used to estimate the abundance of onager in the two main vegetation communities of the park. Onager use of vegetation communities was not significantly different in autumn, winter and spring, but in summer onagers used Artemisia sieberi community significantly more than the Zygophillum-Artemisia community. The most sensible relationships, resulting from multiple regressions, were negative effects of Zygophyllum eurypterum and trough distance. Negative relationship to trough distance showed importance of water resources for onager presence. Population density of onager, estimated through distance sampling, was higher in Artemisia sieberi community (3 onagers per km2 95% confidence interval 1.58–5.7) compared with the Zygophillum-Artemisia community (0.45 onagers per 1 km2 95% confidence interval 028–0.73). The mean density of onager in the national park was about 1.0 onager per km2. Complete protection and suitable distribution of adequate water resources are the main contributing factors to the high density of onagers in QNP.