National Geographic: With hundreds of dead or sick Magellanic penguins washing up along the Brazilian coast in recent weeks, experts are struggling to figure out why so many have been appearing—and why they’re so much farther north than usual. In July and August—winter in South America—it is common for a few dozen young penguins to wash up as far north as Rio de Janeiro state. That’s because each year thousands of the animals living in Patagonia, at the southern tip of South …