Stable isotopes identify age- and sex-specific dietary partitioning and foraging habitat segregation in southern giant petrels breeding in Antarctica and southern Patagonia

Abstract

We examined the isotopic signatures (d 13 C, d 15

Linking foraging behavior and diet in a diving seabird

“…Imperial shag whole blood and plasma, and prey muscle samples were processed according to Raya Rey et al . (). Dry samples were weighed into tin capsules and carbon (δ 13 C) and nitrogen (δ 15 N) values were determined from the flash‐combusted tissues using a Costech (EC4010) elemental analyzer through an interfaced Thermo delta V plus continuous flow stable isotope ratio mass spectrometer (CFIRMS) at the University of North Carolina Wilmington.…”

Sexual and parent–offspring dietary segregation in a colonial raptor as revealed by stable isotopes

“…Niche divergence to reduce intra‐specific competition seems also unlikely to explain sexual segregation in lesser kestrels. Intra‐specific competition can be avoided by using different prey types and foraging habitats (Raya Rey et al ., ; Ludynia et al ., ). However, in our study area, foraging areas of male and female lesser kestrels are known to overlap broadly during the breeding season (Franco et al ., ).…”

“…Sexual segregation in foraging behaviour is generally considered to result from social dominance and competitive exclusion or from niche specialization arising from differences in morphology or reproductive role (Catry et al ., ; Raya Rey et al ., ; Ludynia et al ., ). In sexually size‐dimorphic species, such as the lesser kestrel, the larger sex often requires a higher absolute energy intake to meet metabolic requirements imposed by a larger body mass.…”

“…Among bird populations, dietary segregation between sexes or age groups has often been reported (Forero et al ., ; Catry, Phillips & Croxall, ; Alonso et al ., ; Raya Rey et al ., ; Beaulieu & Sockman, ). Trophic sexual segregation is more spread among sex‐dimorphic species and often linked to niche specialization arising from different morphology or the different roles played by males and females during reproduction (Forero et al ., ; Phillips et al ., ).…”

“…Dietary age segregation, and in particular parent–offspring segregation, has been described to reflect the different nutritional needs of adults and chicks, with the later requiring higher quality prey for a fast developing and improved survival probability (Alonso et al ., ; Raya Rey et al ., ; Beaulieu & Sockman, ). On the other hand, central place foragers are often single‐prey loaders and should thus maximize their rate of energy delivered per provisioning trip (Stephens & Krebs, ).…”