Multiple effects of weather on the starvation and predation risk trade-off in choice of feeding location in Redshanks

1. Animals should choose the feeding habitat that allows them to meet their energy requirements while minimizing predation risk, but as weather becomes more severe, animals may choose riskier, but more profitable, feeding habitats. 2. At the Tyninghame estuary, Scotland, Redshanks (Tringa totanus) chose to feed on either a mudflat or saltmarsh. Energy intake rates were 23% higher and thermoregulatory costs were 40% lower on the saltmarsh, but predation risk from sparrowhawks (Accipiter nisus) was 21 times higher. 3. The investigation tested whether the riskier habitat was chosen only when weather conditions were such that individuals were unable to meet their energy requirements in the safer habitat, and how any additional effects of weather affected this choice. 4. When starvation risk increased on the mudflat, more Redshanks selected the salt-marsh where energy budgets alone accounted for 22% of the variation in habitat choice. Temperature and wind may have had smaller additional, independent effects that were probably related to their effects on vigilance behaviour and predator detection. 5. The results show that weather may be crucial in determining habitat choice through its direct effects on starvation and predation risk, and the importance of considering a wide range of weather conditions when determining habitat requirements.