Emperor penguins' first journey to sea

ANTARCTICA – Emperor penguin chicks hatch into one of Earth’s most inhospitable places – the frozen world of Antarctica. Childhood in this environment is harsh and lasts only about five months, when their formerly doting parents leave the fledglings to fend for themselves.

Photo: Vincent Munier

New research by the Woods Hole Oceanographic Institution (WHOI) and colleagues reveals the previously unknown behaviours of juvenile emperor penguins in their critical early months when they leave their birth colony and first learn how to swim, dive and find food.

The paper, published on 17 January 2019 in Marine Ecology Progress Series, also highlights the unique connection between juvenile diving behaviours and a layer of the ocean known as the thermocline, where warmer surface waters meet cooler deep waters below and where their prey likely gather in groups.

Female penguins are getting stranded along the South American coast

SOUTH AMERICA – Every year, thousands of Magellanic penguins are stranded along the South American coast – from northern Argentina to southern Brazil – 1000 kilometres away from their breeding ground in northern Patagonia. Now researchers have new evidence to explain why 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. Their findings were reported on 7 January 2019 in Current Biology.

Magellanic penguins,
Photo credit: Takashi Yamamoto

"Anthropogenic threats have been considered to threaten wintering Magellanic penguins along the coasts of northern Argentina, Uruguay, and southern Brazil," said Takashi Yamamoto of the Institute of Statistical Mathematics in Tokyo.

"These include water pollution caused by oil development and marine transport as well as fishery-associated hazards, such as by-catch and depletion of prey species.

"Our results suggest that the northward spatial expansion likely increases the probability to suffer these risks, and particularly so in females."

Single male Magellanic penguin numbers rising at Punta Tombo

ARGENTINA – Like most of their stout-bodied, flippered kin, Magellanic penguins spend much of their lives in the ocean. From late autumn through winter and into spring in the Southern Hemisphere, these South American penguins swim off the coast of southern Brazil, Uruguay and northern Argentina in search of anchovies, sardines and squid.

A young male Magellanic penguin.
Photo: Natasha Gownaris

But as spring turns to summer, they swim thousands of miles south and congregate in big coastal colonies. There, males and females pair off, breed and attempt to rear one or two newly hatched chicks. One of the largest breeding colonies for Magellanic penguins is at Punta Tombo in Argentina, where University of Washington (UW) biology professor P. Dee Boersma and her team at the Center for Ecosystem Sentinels have studied the penguins since 1982. They have documented a population decline at Punta Tombo of more than 40 percent since 1987, along with a rising male-to-female ratio, and have spent years trying to pinpoint its cause.

In a paper published on 2 January 2019 in the journal Ecological Applications, Boersma and UW postdoctoral researcher Natasha Gownaris report that juvenile females are more likely to die at sea, which has caused a skewed sex ratio of nearly three males to every female, as well as population decline. Their study incorporated more than 30 years of population data collected by UW researchers – including banding and studying individual penguins – into models of population dynamics.