Timing of reproductive events in relation to environmental conditions is essential to optimize survival and reproductive success. Rapid global warming challenges the plasticity of life-history traits, affecting population viability. In this master project I will investigate whether calving dates in Svalbard reindeer respond to variation in onset of spring as well as to trends of advanced spring phenology. I will retrieve (i.e. download) data from GPS-marked animals that will be used to deduce calving dates for recent years, for comparison with previous years' data.