Foraging specialization and body size in seabirds

Abstract

Body size affects many biological processes since it predicts traits, timing, and biological rates. Some of these relationships are explained by the metabolic theory of ecology, which predicts that they should scale according to a power law with exponents multiples of [Formula]. Here we study the relationships between foraging specialization, particularly the number of dietary categories and prey capture strategies, and seabird species size, based on a database of 342 species (representing more than 95 % of all species). In our analysis, we found a negative relationship between the number of dietary categories and the number of capture strategies with body size with exponents of -0.83{+/-}0.31 and -0.76{+/-}0.06. To explain these relationships in terms of first principles, we developed a simple model to explain the origin of this scaling based on well-established ecological scaling relationships. Our study suggests that foraging specialization is constrained by the energy used by an organism, providing a basis for future theoretical developments.