Reproductive performance in arctic-nesting geese is influenced by environmental conditions during the wintering, breeding and migration seasons

Arctic regions are expected to experience pronounced changes in climate during the current century. Large numbers of waterfowl breed in these regions, and any climate induced changes are likely to have consequences for their demographics. Moreover, environmental changes experienced during migration and on the wintering grounds may also have impacts but remain poorly understood. We investigate the role of climate variation during breeding, migration and wintering, while controlling for possible effects of mammalian predation and density dependence on the reproduction of Svalbard breeding barnacle geese Branta leucopsis using 40 years of observations. Breeding success was significantly positively correlated with temperature on both the wintering grounds (Scotland) and breeding grounds (Svalbard), but negatively correlated with the number of days of strong cross-winds during the northward migration period. These factors remained significant when controlling for a strong negative effect of population size. Goose reproduction on Svalbard was also linked to fluctuations in arctic fox Alopex lagopus populations occurring elsewhere in the arctic. This reveals the importance of mammalian predation, which may vary as a non-linear function of conditions within the wider arctic region. Climate predictions were used to project barnacle goose reproduction and hence the population until 2050. These simulations suggest the population will grow at between 1% and 2.7% per year, in response to increasing temperatures. However, it is harder to predict how changes in other factors, such as reductions in sea ice, may impact on arctic breeding birds.