Why am I writing about Magellanic penguins from South America now instead of African penguins? For one thing, Magellanic penguins’ conservation status is near threatened, so we need to better understand them if we want to prevent further population declines. More importantly, African and Magellanic penguins are extremely close relatives, so research findings in one species may be applicable to the other.
In a recent study, researchers monitored a colony of Magellanic penguins at Punta Tombo, Argentina, by banding approximately 44,000 chicks over the course of 33 years [1]. The researchers determined the sex of 57% of the penguins they banded and tracked the individuals throughout the years [1].
During the non-breeding season, when Magellanic penguin mortality is at its highest, the researchers discovered that females have a lower survival rate than males, whose survival rate is 33.3% greater than that of females [1].
Moreover, female Magellanic penguins suffer their highest mortality rate as juveniles, rather than adults, possibly because they are less efficient at foraging [1].
The researchers determined that this sex bias in survival is responsible for the Punta Tambo population decline from 1990 to 2009, which is roughly 40% (determined starting in 1987, documented in scientific literature in 1990) [1].
The authors hope that management of fisheries and habitat space could mitigate the loss of females and thus, further decline of Magellanic species [1]. They also stress the importance of determining sex bias in survival rates for other seabird colonies to accurately monitor their populations [1].
Because African penguins are genetically similar to Magellanic penguins, I think that an assessment of sex-biased survival in African penguins could help to examine additional causes of population decline and introduce new tactics to preserve this endangered species. Studies on Magellanic penguins could save their cousins from across the Atlantic.
References:
- Gownaris N. J., and P. D. Boersma. 2019. Sex-biased survival contributes to population decline in a long-lived seabird, the Magellanic penguin. Ecological Applications 29(1): e01826. 10.1002/eap.1826.
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The Penguin Researcher 