UC Davis

Ecological dynamics have been altered by recent climate change in regions with pronounced warming trends. Landscape- and regional-scale ecological processes face change in both seasonal patterns and long-term trends as temperature and precipitation regimes shift. Interspecific interactions are especially sensitive to environmental change if one species responds flexibly to abiotic processes but the other does not. Herbivore movements, migrations, and distributions – each of which relate to biotic and abiotic environmental variation – are thus likely to change as effects of climate change cascade through ecosystems. Yet, multilevel relationships connecting climate with spatial dynamics of herbivores are poorly understood, in part due to the difficulties in generating consistent measurements of fine-scale ecological processes across broad geographic extents. Here, I use the Sierra Nevada mountains of California and Sierra Nevada bighorn sheep (Ovis canadensis sierrae, hereafter “Sierra bighorn”) as a model to address three questions about space and time in ungulate ecology: First, how does landscape phenology vary along a desert-alpine gradient? Second, what drives nomadic migration in Sierra bighorn? And third, how can long-term climate forecasts inform conservation of large ungulates at the continental scale? I begin by outlining a niche-centric view of altitudinal migration and its marine counterpart, bathymetric migration. I then quantify relationships among topography, geography, and weather, and their collective effects on spatial patterns in resource phenology. Next, I address movement strategy, organization, and migration timing of an alpine specialist as they relate to the resource base. Finally, I contextualize ungulate conservation efforts in future climatic conditions, identifying which species are most susceptible to loss of protected climate space toward the end of the century.