A. High tech with traditional life at Green Bank.

    Over millions of years, penguins（企鹅）have developed a keen sense of where to find food. Once they're old enough, they set off from the shores on which they were hatched for the first time and swim long distances in search of tasty fish like anchovies and sardines. But they don't search directly for the fish themselves.

    For example, when young African penguins head out to sea, they look for areas with low surface temperatures and high chlorophyll(叶绿素) because those conditions signal the presence of phytoplankton（浮游植物）. And lots of phytoplankton means lots of plankton（浮游动物）, which in turn means lots of their favorite fish. Well, that's what it used to mean.

    Climate change plus overfishing have made the penguin feeding grounds a mirage(海市蜃楼). The habitat is indeed plankton-rich—but now it's fish-poor. Researchers call this an “ecological trap.”

    “It's a situation where you have a signal that previously pointed an animal towards good quality habitat. That habitat's been changed, usually by human pressures. The signal stays, but the quality in the environment deteriorates.”

    Richard Sherley, a zoologist at the University of Exeter and his team used satellite imaging to track the African penguins from eight sites along southern Africa. Historically, the birds benefited from tons of fish off the coasts of Angola, Namibia and western South Africa, but now they're going hungry.

    “I was really hoping we'd see them going east, and finding areas where the fish had moved to but it ends up being quite a sad story for the penguins.” said Richard.

    The researchers calculate that by falling into this ecological trap, African penguin populations on South Africa's Western Cape have declined by around 80 percent.

    Some research groups are exploring the idea of moving chicks to a place where they can't get trapped, like the Eastern Cape. But Sherley thinks that a longer-term solution means making and carrying out rules to create more sustainable(可持续的) fishing industry, something that he says needs public support.