Arctic amplification, the accelerated climate warming in the polar regions, is causing a more rapid advancement of the onset of spring in the Arctic than in temperate regions.Consequently, the arrival of many migratory birds in the Arctic is thought to become increasingly mismatched with the onset of local spring, consequently reducing individual fitness and potentially even population levels. We used a dynamic state variable model to study whether Arctic long-distance migrants can advance their migratory schedules under climate warming scenarios which include Arctic amplification, and whether such an advancement is constrained by fuel accumulation or the ability to anticipate climatic changes. Our model predicts that barnacle geese Branta leucopsis suffer from considerably reduced reproductive success with increasing Arctic amplification through mistimed arrival, when they cannot anticipate a more rapid progress of Arctic spring from their wintering grounds. When geese are able to anticipate a more rapid progress of Arctic spring, they are predicted to advance their spring arrival under Arctic amplification up to 44 days without any reproductive costs in terms of optimal condition or timing of breeding. Negative effects of mistimed arrival on reproduction are predicted to be somewhat mitigated by increasing summer length under warming in the Arctic, as late arriving geese can still breed successfully. We conclude that adaptation to Arctic amplification may rather be constrained by the (un)predictability of changes in the Arctic spring than by the time available for fuel accumulation. Social migrants like geese tend to have a high behavioural plasticity regarding stopover site choice and migration schedule, giving them the potential to adapt to future climate changes on their flyway. K E Y W O R D SBranta leucopsis, climate change, dynamic state variable model, global warming, mistimed arrival

Abstract. 1. In Western Europe, the diving beetle Dytiscus latissimus (Coleoptera: Dytiscidae) has become rare and went extinct in several countries during the last century. This study investigated whether larval development rate, metabolism and feeding ecology differ between D. latissimus and the congeneric D. lapponicus to explore factors explaining its decline.2. During instar I and II, D. latissimus larvae developed faster and gained more weight than D. lapponicus larvae. In accordance, D. latissimus larvae had higher oxygen consumption rates than D. lapponicus larvae, which signifies a greater energy expenditure.3. Food preference tests showed that D. latissimus larvae strongly prefer caddisfly larvae (Trichoptera: Limnephilidae) with early instars being obligatory dependent on caddisfly larvae for their development. Only instar III larvae readily fed on alternative prey items. In contrast, D. lapponicus larvae had a broader diet and even rejected caddisfly larvae.4. Based on field observations, availability of caddisfly larvae strongly declined before the end of the larval development of D. latissimus, suggesting that time constraints on food availability limit completion of larval development.5. Our results suggest that food limitation during (early) larval stages is a possible bottle-neck for this species, potentially explaining its disappearance from former localities. Promoting caddisfly larvae in the vicinity of D. latissimus oviposition sites, may possibly safeguard the present distribution of D. latissimus and support the species recovery. Although more research is needed, promoting leaf litter in shores may be beneficial to the shredding caddisfly larvae and in turn for their predator D. latissimus.