Project - How can Arctic-nesting geese cope with Arctic amplification?

Summary

Most Arctic-nesting birds are long-distance migrants, wintering in tropical or temperate regions, many of those in The Netherlands (e.g., 85% of the flyway population of barnacle geese). Because climate is warming more rapidly in the Arctic than elsewhere on earth (Arctic amplification), the question arises how these birds can cope with these changes. On the one hand, the birds may arrive too late, and/or with too little body stores, to profit from the spring food peak. On the other hand, they may benefit from the longer summer season, which may enhance the survival of their young. We make use of the unique feature that barnacle geese have recently greatly extended their breeding range to lower latitudes, enabling the comparison of breeding strategies at different temperature regimes. We aim to determine the specific relationship between arrival time/condition and subsequent breeding performance (the so-called terminal reward function). Timing of migration will be determined by tracking the birds with satellite transmitters and geolocators. Breeding condition will be inferred from body weights during incubation and incubation constancy (females lose weight during incubation). We also measure the expected changes in food plant biomass and quality by warming the vegetation in open-top chambers. Together, these data will enable us to model bird migration with dynamic programming, and inform us how breeding output might change under future scenarios. Such a behaviour-based model will form an important component of future new generation population models that can inform policy-makers about the most appropriate measures to manage the goose population.