Big dads carry weight among wandering albatrosses

Dad bod is a big deal for albatrosses. Bigger male wandering albatrosses live longer and are more likely to breed successfully compared with lighter birds, while mass has no observable effect on female breeding or survival, researchers report May 3 in Proceedings of the Royal Society B.

Climate change could shift the degree to which some seabirds pack on the pounds. It’s unclear how those shifts will play out in species like wandering albatrosses (Diomedea exulans), in which males are much bigger than females.

To investigate, Tina Cornioley of the University of Zurich and her colleagues examined how body mass affects certain aspects of an albatross’s life — survival, odds of mating, having chicks, chick size and chick survival. From 1988 to 2013, the team tracked 662 adult albatrosses on Possession Island in the southern Indian Ocean. Albatross parents take turns sitting on their eggs, but dads actually invest more energy in rearing chicks after they hatch.

In addition to the survival and breeding advantages, the team also found that heavier dads were more likely to have heavier sons, but not daughters, and those sons had better survival odds. Although the team can’t rule out the possibility of a genetic element, the fact that body mass fluctuates throughout a bird’s life and the absence of the trend in mothers and daughters makes genetics a less likely explanation, says Cornioley. Instead, the researchers think that heftier dads invest more in sons than daughters.