Acquisition of foraging skills by Heron Island Silvereyes Zosterops later alis chlorocephala

Abstract

Age‐related differences in foraging efficiency and behaviour were investigated in a population of colour‐ringed Silvereyes Zosterops lateralis. First‐year birds were less efficient foragers than older birds with second‐year birds being intermediate. First‐ and second‐year birds had lower success rates than older birds overall, and for most capture techniques and substrates. First‐year birds never attempted breeding while about half of the second‐year birds and all of the older birds did. Both learning and selection effects may have been involved in causing the age‐related differences in foraging behaviour. Foraging skills appear to improve during the first 2 years of life and selection could remove the least efficient foragers from the population in winter when food is short. That second‐year birds, some of which had already attempted breeding, were not significantly more efficient foragers than first‐year birds suggests that reproduction is not delayed until adult levels of foraging efficiency have been attained.