McComb-Turbitt SP, Crossin GT, Tierney M, Brickle P, Trathan P, Williams TD, Auger-Méthé M

Diving efficiency at depth and pre-breeding foraging effort increase with haemoglobin levels in gentoo penguins

Efficient foraging over the winter can be critical to the breeding success of seabirds in the spring. McComb-Turbitt and co-authors show that gentoo penguins with higher haemoglobin levels make more frequent and efficient deep dives (140 m) prior to breeding. This relationship can be explained by the increased aerobic capacity provided by elevated levels of haemoglobin and could allow some individuals to reach food resources not accessible to others. In addition, early-laying penguins spent less time at sea than non-breeders, suggesting that more efficient foragers can breed earlier. Given the impacts of egg production on haemoglobin levels, these results highlight the need to disentangle the trade-offs between aerobic condition and breeding.

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