HABITAT CHOICES OF NUBIAN IBEX (CAPRA NUBIANA) EVALUATED WITH A HABITAT SUITABILITY MODELING AND ISODAR ANALYSIS

作者：Tadesse Solomon A^*; Kotler Burt P

来源：Israel Journal of Ecology & Evolution, 2010, 56(1): 55-74.

DOI：10.1560/IJEE.56.1.55

• habitat characteristics
• energetic costs of foraging
• predation costs
• foraging opportunities available in other habitats
• Nubian ibex (Capra nubiana)
• habitat suitability index (HSI) model
• isodars

The value of a habitat for a forager may be affected by habitat characteristics related to food availability, energetic costs of foraging, predation costs, and the foraging opportunities available in other habitats. Nubian ibex (Capra nubiana) are stout, sure-footed social wild goats that inhabit arid landscapes with steep terrain. We investigated their habitat selection behavior using indicators to (1) develop a habitat suitability index (HSI) model that would account for the variation in the activity densities of Nubian ibex across habitat types and seasons, (2) apply the isodar technique to look for density-dependent habitat selection behavior in Nubian ibex, and (3) investigate the proximate environmental factors that correlate to relative activity densities of Nubian ibex. We determined relative densities of the ibex by recording sightings of animals along standard walking transects. We incorporated the habitat variables that had greatest influence on the densities of Nubian ibex into habitat suitability index models for both spring and summer seasons.
The HSI models revealed that Nubian ibex most preferred open cliff face habitat offering safety during the spring season, but their habitat preference shifted towards an area with watered gardens ("grave area habitat") during the summer season. Significant isodars were only obtained for the summer season comparisons between grave area versus cliff face, and between grave area versus plateau habitats. The slopes of the isodars suggest that the grave area habitat is 10.5 and 7.6 times more productive than the plateau and the cliff face habitats, respectively. Our results suggest that the relative abundances and habitat preferences of Nubian ibex varied with the seasonal availability of habitat resources, extent of predation risks, and human nuisance disturbances across the landscape. We recommend that wildlife managers dealing with the conservation and protection of the endangered Nubian ibex should focus on the various ecological and anthropogenic factors governing the habitat selection and preferences.

• 出版日期2010