The Mystery of the Macaroni Penguin and the Bad Egg

Given an allotment of two eggs each year, a lady macaroni penguin starts out by laying a smallish bad egg--then she goes on to lay a bigger, good one. If all goes well, the big egg hatches into a baby bird, but the smaller one never does. Why bother laying an egg that never hatches? A new study doesn't touch that 60-year-old question, but it does hint that the smaller eggs' sizes might result from the macaroni's migration. A group led by bird biologist Glenn T. Crossin has looked at the size of the bad eggs, which can be anywhere from almost the size of a hatching egg to fifty percent smaller. They noted that some ladies laid their eggs immediately after arriving at a penguin colony, while others waited a couple of weeks--and suspected that some of the penguins formed their eggs en route. By measuring the levels of ...