Individual specialization in the foraging and feeding strategies of seabirds: a review

Abstract

Trophic relationships are a central theme in ecology and play a crucial role in the survival of organisms, because the availability of food resources varies over time and space. Until recently, most ecological studies treated conspecific individuals as ecologically equivalent, but intra-specific variation in individual foraging and feeding strategies can be large. Studies documenting the occurrence of individual specialization in seabirds (n = 94) increased substantially since the year 2000, and rapid and significant advances are being made since then. This review summarizes existing knowledge within this subject, examines the relative incidence of individual specialization and investigates the possible ecological implications of individual specialization in seabirds. Our results show that, to date, the incidence of individual specialization is documented in around 12 % of the total extant seabird species although some studies (n = 12) did not find evidences of individual specialization in the foraging and feeding strategies of some seabird populations. Most studies were conducted at higher latitudes, leading to a lack of knowledge on the incidence of this trait in tropical seabird populations. Results suggest that the incidence of individual specialization may be potentially widespread within seabirds, but may fluctuate spatio-temporally among/within species and populations due to the frequency of specialists, predictability of resources or environmental conditions. This study supports the hypothesis that individual specialization may have important ecological consequences at both individual and population levels, such as implications in breeding performance or in intra-specific competition and, consequently, a high impact on ecological processes and foraging dynamics. Further investigation is required to identify the mechanisms that generate individual specialization and its ecological implications at both population and individual levels.