A review of estimates of daily energy expenditure and food intake in cormorants ( Phalacrocorax spp.)

Abstract

Daily energy expenditure (DEE) and daily food intake (DFI) are key parameters in estimating population level consumption by cormorants. A number of different methods are still employed in estimating these parameters along with different estimates for assimilation efficiency (if used) and prey energy density. The pellet/fish size reconstruction and percent adult body weight methods underestimate DFI for a number of reasons including an implied underestimation of DEE. In the absence of study-specific data, an assimilation efficiency of 0.80 and prey energy density of 5.42 kJ∙g − 1 are recommended. The bioenergetic model for field metabolic rate from Ellis and Gabrielsen (2002) is recommended for adults during the nesting season and their model for basal metabolic rate (BMR × 2.5) is recommended for adults or sub-adults outside the nesting season. Comparisons between empirical and bioenergetic models for chick DFI are also made with recommendations on estimating DFI.