Flexible foraging behaviour of a sexually dimorphic seabird: Large males do not always dive deep

摘要: Sex differences in foraging behaviour have been explained by size dimorphism and/or avoidance of inter-sexual competition for depletable resources. To distinguish between these 2 hypotheses, we examined how intrinsic factors (sex-related differences) and extrinsic (year shape the size-dimorphic imperial shags Phalacrocorax atriceps albiventer breeding at New Island, Falkland Islands/Islas Malvinas. We deployed time-depth compass loggers to male female over 3 consecutive chick-feeding seasons. Males females partly overlapped coastal areas, which were used mainly benthic diving. additionally offshore areas deep water shallow pelagic diving, suggesting that spatial segregation is involved food. Stable isotope data suggested prey composition sexes, with consistently higher trophic levels males, as expected their larger size. 27% heavier than reached greater maximum dive depths (98.9 ± 5.3 m) (54.1 2.9 m). However, contrary pre- dictions based on body dimorphism, median males similar those females. While more flexible behaviour. Females also carried out dives per day all years, deeper longer one year. As parameters differed strongly among our results suggest food are evolution sex-related this species.