When ethologist Konrad Lorenz famously raised a flock of geese in the 1930s, they "imprinted" on him, following him around and treating him like their mother. But for so-called "parasitic" animals, growing up with another species is normal. Redhead ducks, for example, frequently lay their eggs in canvasback duck nests to co-opt the other ducks' energy and food for their own young. So how do they avoid the lifelong confusion that plagued Lorenz's geese? They don't, researchers report online tomorrow in the Proceedings of the Royal Society B. Scientists swapped ducklings, raising 16 male canvasbacks among redheads and 16 male redheads among canvasbacks, and found that early cross-species imprinting led to courtship chaos for both parasitic and nonparasitic ducks. The canvasback-raised redhead males pursued canvasback females instead of fellow redheads, and redhead-raised canvasbacks (like the male pictured above left) courted redhead females (above right)—and met with hostile rejections. The findings reveal that even parasitic animals aren't safe from the confusion of cross-species imprinting, and leave unanswered the question of how redhead ducks eventually find their way back to their wintering grounds and the company of their own kind.
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