High levels of energy expenditure in shorebirds: metabolic adaptations to an energetically expensive way of life

Abstract

Measured basal metabolic rate (BMR), existence metabolism and costs of thermoregulation in oystercatcher Haematopus ostralegus, grey plover Pluvialis squatarola and turnstone Arenaria interpres. A high DEE (daily energy expenditure) mainly generated by the skeletal muscles, requires a high level of support by the organs in the abdominal cavity, which inevitably results in a high BMR. This interpretation provides a functional explanation for the constant ratio between BMR and DEE in many bird species and explains the existence of a "maximum sustained working level' of parent birds feeding their young at c4 times BMR. The high DEE of temperate wintering shorebirds must be considered in relation to peak energy demands during their annual cycle. Candidate times are the periods of pre-migratory fattening and mid-winter. From measurements of food intake the authors estimated the additional amount of energy needed for 1 g increase in body weight at 45.66 kJ. Using this value, the efficiency of energy deposition is 88%. -from Authors