Pushed for time or saving on fuel: fine-scale energy budgets shed light on currencies in a diving bird

摘要: Animals may forage using different currencies depending on whether time minimization or energy maximization is more pertinent at the time. Assessment of net acquisition requires detailed information instantaneous activity-specific power use, which varies according to animal performance, being influenced, for example, by speed and prey loading, has not been measured before in wild animals. We used a new proxy expenditure (overall dynamic body acceleration), quantify foraging effort model species, imperial shag Phalacrocorax atriceps, during diving. Power costs varied nonlinearly with depth exploited owing depth-related buoyancy. Consequently, solutions maximizing gross rate gain energetic efficiency differed dives any given depth. Dive free-ranging shags breeding season was consistent strategy maximize gain. suggest that divergence dive implications measurement across diverse diving taxa.