Variation in daily and seasonal foraging routines of non-breeding barnacle geese (Branta leucopsis): working harder does not overcome environmental constraints

摘要: This study describes the changes in stored body fat Svalbard barnacle geese Branta leucopsis over non-breeding period, and uses behavioural patterns to explain variation stores. It was predicted that foraging effort would: (1) increase at low food densities; (2) when days were short; (3) decrease smaller flocks; (4) be bimodally distributed throughout day for long days, but constant short days. Time constraints found major driving force behind decisions during shortest of mid-winter, whereas density drive longer Field observations stores showed rapidly accumulated start end remained mid-winter. is suggested length prevented a positive storage rate mid-winter through limitation time, even though high this period. During single day, evidence bimodal routine found, where feeding activity concentrated early morning late afternoon periods. pattern full range lengths, which suggests must interrupted so other essential activities can conducted. concluded choices constrained by environmental conditions, these allow explained.