January 7, 2019, Cell Press
Every year, thousands of
Magellanic penguins are stranded along the South American coast—from northern
Argentina to southern Brazil—1,000 kilometers away from their breeding ground
in northern Patagonia. Now researchers reporting in Current Biology on
January 7 have new evidence to explain the observation that the stranded birds
are most often female: female penguins venture farther north than males do,
where they are apparently more likely to run into trouble.
"Anthropogenic threats have
been considered to threaten wintering Magellanic penguins along the coasts of
northern Argentina, Uruguay, and southern Brazil; these include water pollution caused
by oil development and
marine transport as well as fishery-associated hazards, such as bycatch and
depletion of prey species," says Takashi Yamamoto of the Institute of
Statistical Mathematics in Tokyo. "Our results suggest that the northward
spatial expansion likely increases the probability to suffer these risks, and
particularly so in females."
Researchers knew that penguins
stranded along the South American coast were three times as likely to be
females. The question was: why?
While data were lacking, there
wasn't any evidence to suggest that males and females split up for the winter.
Now, Yamamoto and his colleagues find that in fact they do. The researchers
recorded the migratory and diving behavior of 14 Magellanic penguins (eight
males and six females) during the non-breeding period in 2017 using LAT 2500
geolocators (Lotek Wireless, Inc.).
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