Movement ecology of female alpine ibex (Capra ibex): influence of resources, climate, and reproductive constraints

Field: Agricultural and Biological Sciences (Life Sciences)

There is now ample evidence of the ecological impacts of recent climate change on Alpine ecosystems. Animal populations, and in particular herbivores, can be affected directly, through modifications of the environmental temperature, and indirectly, through alteration of both distribution and phenology of plant communities. Understanding the behavioral strategies and tactics that populations and individuals use to buffer climatic variability and its impacts are particularly relevant in order to evaluate their vulnerability to climate change and develop incisive management and conservation actions. This dissertation investigates how females of Alpine ibex (Capra ibex) taken as a model for specialized Alpine large herbivore species, shape their behavior to deal with environmental and climatic variation and reproductive constraints during summer, a crucial period for the fitness of females of a capital breeder species. For this purpose, I used GPS locations and activity data of 22 females monitored in the Marmolada massif (northeastern Italian Alps) from 2010 to 2016. I tested for differences in space use and activity patterns of female ibex at different temporal scales (annual, intra-seasonal and hourly), in relation with changes in temperature, habitat type, and food resource availability -productivity (NDVI) and green up (?NDVI) of vegetation-. In addition, I evaluated anti-predator behavior contrasting the tactics of use of refuge areas and habitat types of females with different reproductive status. My findings showed how female ibex vary the use of space, habitat selection and rhythms of activity in a continuous trade off that allow them to fulfill different physiological needs in response to variation in environmental and climatic conditions, and under reproductive constraint. Ibex females responded to the altitudinal gradient in vegetation productivity with an altitudinal shift in spring and summer, to exploit the vegetation in earlier phenological stages. At the same time, females avoided thermal stress and maintained constant the daily foraging time through adjustments in circadian activity rhythms and altitudinal shifts. Moreover, during the reproductive period females with kids modified their movement patterns, feeding activity, and habitat use cope with increased energetic demands and the need of protecting kids with their limited locomotion capacity. My results have shown that the spatial behaviors that act at different scales were an effective strategy to optimize thermoregulation needs and forage acquisition while reducing predation risk. This thesis enriches knowledge on the influence of resources, climate, and reproductive constraints on behavioral strategies and tactics of female ibex. It represents the first attempt for this species, to my knowledge, to describe these behavioral responses as part of a complex trade-off mechanism, which occurs across different temporal scales, highlighting a presence of behavioral plasticity in ibex females. Such behavioral plasticity may allow them to buffer the environmental variations associated with current climate change.