Measuring Field Metabolic Rates

This chapter describes various techniques for measuring metabolic rates of unrestrained organisms in the field. These include stable isotope techniques, which allow the accurate measurement of the carbon dioxide production of wild animals over an interval ranging from a few hours to several days. The main disadvantage of the method is that the measurement is integrative and the organism must be captured on at least two occasions. Alternative techniques for real-time measurement of metabolic rates utilizing flow-through respirometry in wild, unrestrained animals are described, including representative case studies measuring hovering metabolism in wild hummingbirds, the foraging energetics of ants in the wild, and the energetics of nest building in wasps.