Life-history, demography and behaviour of the Alpine chamois (Rupicapra rupicapra): the role of climate and environmental change

Abstract

Climate change is altering ecology in myriad ways; the distributions, dynamics, phenology, morphology and life-histories of species are changing. Establishing the relative importance of these changes in different ecological traits is important to fully understand how climate and environmental change threatens populations. However, until recently, studies have often focused solely on range-shift responses and have rarely examined multiple forms of ecological change in a single species. Case-studies focusing on multiple aspects of ecology, for example demography, life-history and behaviour, could provide important general insights into how climate change will most threaten the persistence of species and populations. In this thesis, I investigate ecological variation, and the influence of climate and environmental change, in a common species of considerable cultural, economic and ecological importance, the Alpine chamois (Rupicapra rupicapra). Using a 38-year dataset on body masses and demography, augmented with demographic and behavioural data collected during this thesis, I examine variation in the life-history, demography and behaviour of this species, making both species-specific and general inferences. I find variability in reproductive strategies in the study populations, providing considerable insight into poorly understood area of this species’ ecology. Male chamois in neighbouring populations adopt contrasting reproductive strategies, likely due to climatic differences among areas. Interestingly though, males time investment in reproduction similarly in the different populations. However, there is a strong pattern of age-dependent investment; young males delay reproduction until the end of the breeding season, apparently as a strategy to avoid high levels of competition. This is the first clear evidence for such a strategy in a male mammal. Next, focussing on the effect of climatic and environmental factors on chamois ecology, I found a strong influence of climate on body size, demography and foraging behaviour. Climate change appears to be driving declines in body size and climatic variation exerts a strong influence on demographic variation and foraging behaviour. However, the effects of local anthropogenic drivers in some cases exceed these effects. High hunting pressure has a profound effect on survival, with hunting mortality largely replacing natural mortality. Furthermore, the influence of disturbance by livestock grazing on altitudinal migration is very pronounced, forcing chamois to much higher altitudes. This project illustrates that climate change can affect diverse aspects of ecology. Despite the overriding research focus on range-shifts, climate-driven life-history and demographic change could influence populations more strongly. Furthermore, my results show that effects of other drivers, such as harvesting and biotic interactions, can also have profound effects on ecology, at times exceeding the influence of climate.