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 a protein called vitellogenin–essential for egg making–in arriving penguins, Crossin’s team realized that the ladies who waited before laying the first egg had greater levels of the protein (and possibly bigger first eggs), while those who laid immediately had lower protein levels (resulting in smaller eggs). They suspect that the little-egg makers aren’t “reproductively ready” when they pop the first one out.
“The thinking is that evolution works perfectly, but that’s not always the case, and the macaroni penguin is one good example of that,” he said.
Maybe the smug penguin couldn’t be bothered to evolve any further once it had stuck a feather on its head and called it macaroni.
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Image: flickr / Jason Auch