AGE-DEPENDENT CHOICE OF REDSHANK (TRINGA-TOTANUS) FEEDING LOCATION - PROFITABILITY OR RISK

1. The effect of a varying risk of predation by sparrowhawks (Accipite r nisus L.) on choice of overwinter feeding site was studied for redsh ank (Tringa totanus L.), on a small Scottish estuary at low tide. 2. A dult and juvenile redshank segregated into two areas, a mussel bed and a salt-marsh area, respectively. Juveniles were excluded from the mus sel beds by the adults, but there were no aggressive interactions on t he salt-marsh. Adults occasionally fed on the salt-marsh, particularly late in the winter. 3. A redshank on the salt-marsh was 4.8 times mor e likely to be killed on the salt-marsh than on the mussel beds. Redsh ank on the salt-marsh fed closer to cover, than those on the mussel be ds: sparrowhawk attack success rate declined as redshank fed further f rom cover. 4. A redshank on the salt-marsh had a much higher foraging rate and overall energy intake rate (1.7 times) than a redshank foragi ng on the mussel beds. Adults on the mussel beds minimized risk of pre dation, rather than maximizing intake rate at low tide. 5. Despite hig her energy intake rate anywhere on the salt-marsh compared to the muss el beds, juveniles on the salt-marsh fed very close to cover, and cons equently at a greater risk of predation. Foraging rates were highest v ery close to cover. Although juveniles were forced to feed on the salt -marsh, they maximized intake, rather than minimizing predation with r espect to choice of feeding location within the salt-marsh.