Prey use and nutritional differences between reproductive states and age classes in Atlantic spotted dolphins (Stenella frontalis) in the Bahamas

摘要

Nutritional quality of prey is a significant driver of predator foraging patterns. In mammals, nutritional needs are known to change across ontogeny and reproductive state; however, little is known about nutrition in marine mammals. For this study, we used observational data of diurnal foraging events, collected annually from 1992 to 2009, to investigate nutrition and prey use in Atlantic spotted dolphins (Stenella frontalis) on Little Bahama Bank, Bahamas, between reproductive states (lactating, pregnant, nonreproductively active [NRA]. We also investigated the impact of age class association (various calf age groups [ages 1-6], older noncalf juveniles, and adults) on foraging group nutrition and prey use. To obtain representative nutrient values, we measured calories, lipids, proteins, and moisture in common prey. Using nutritional values and observational data, we investigated the influence of nutritional value on prey use. Results indicated that specific nutrients were targeted by different reproductive states and age class groups. Nutritional intake of all nutrients was higher for lactating females than pregnant females, but lower than NRA females. Investigation of age group associations revealed that nutritional intake of all four nutrients was higher for noncalf than calf-associated groups. This study represents one of the first investigations of intraspecific prey use and nutritional differences in cetaceans.