Mate fidelity is the norm among Magellanic penguins; "we have one pair of birds that have been faithful for 17 years," says Boersma. But for the male Magellanic, unattached bachelors can pose an additional problem. Because of the large number of females that died last year, there are more than ever this year, and according to Boersma, they are up to their old tricks.
Bachelors wait until a female is alone on her nest, and then try to move in with her. If her mate doesn't return quickly enough, and she begins to get hungry, she'll trust the bachelor to guard the nest while she goes off in search of food. But penguin bachelors are notoriously poor babysitters, and frequently leave the nest, making it extremely vulnerable to predators.
"Her eggs are lost, and what the female remembers [the following year] is that she was not successful with her mate; he wasn't around when she needed him," says Boersma. "But the bachelor, he seemed to be around a lot, so the female divorces her former mate and pairs up with the bachelor. Female choice becomes important when the sex ratio is so skewed."
The egg-to-fledgling survival rate is low; typically one chick for every two breeding pairs survives. Despite the hazards of predators and bachelors, the two biggest threats to chick mortality are flooding and starvation.
Implications for Conservation
Since 1983, more than 50,000 birds have been banded under the Magellanic Penguin Project. One male, named Grease, has been followed since 1982 when he was raising chicks. Until Boersma began her research, scientists assumed that Magellanic penguins stayed fairly close to home on their foraging trips, within 20 miles (30 kilometers) or so. Boersma's data shows the foraging range is much more extensive; some penguins have been tracked more than 600 miles (1,000 kilometers) away.
Boersma's research enables WCS and other organizations to identify potential threats and target conservation efforts.
Oil pollution from tankers discharging ballast water, for instance, has become an increasing threat. Oil pollution kills more than 40,000 Magellanic penguins along the coast of Argentina each year, estimates the International Penguin Conservation Work Group. WCS, teaming with other environmental groups, successfully campaigned to have oil tanker routes moved farther off the coast. WCS and Fundacin Patagonia Natural were instrumental in getting Patagonia's Coastal Zone Management Plan adopted by the Argentina government.
A lot of research questions remain unanswered: Do couples stay together during their six months at sea; do birds that consistently raise chicks know better places to forage, or are they just better at catching fish; how does climate variation change foraging patternsthe questions are endless and Boersma wants to know it all.
"Penguins tell us a lot about environmental change and the quality of change," says Boersma. "Some of the earliest signs of climate change or environmental degradation to the marine environment will be reflected in penguin populations.
"To really learn about these animals takes a lot of financial support, and it has to come from the public," she says. "The government doesn't pay for this kind of research, and universities don't pay for it. If people are interested in supporting research like this, they should find an organization and contribute."
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