Brush turkey chick robot.
CREDIT: A. GÖTH
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How do you know how to find your mates if you grow up alone and don't have a mirror? Such is the dilemma of the Australian brush turkey, which hatches buried in a warm mound of rotting leaf litter.
"Megapodes are the only birds in the world that don't incubate their eggs, so they don't have any chance to learn from their parents what a conspecific looks like," says Ann Göth, a behavioral ecologist at Macquarie University in Sydney, Australia. Females lay eggs in the compost, then leave the incubation up to the heat from the decomposition.
To find out what visual cues a newly hatched chick uses, Göth and colleagues made remote-control brush turkey robots out of toy car motors and the skins of dead chicks. They then presented live chicks with a choice of robots. The chicks found a pecking imposter more attractive than either a still robot or one turning from side to side. And when ultraviolet light was filtered out, the chicks lost interest even in pecking robots, suggesting that they recognize both specific movement patterns and color, the scientists report in the 1 June Journal of Experimental Biology.
Megapodes are an exception to the dogma that birds "imprint," or learn their identity from parents while the nervous system is still at an impressionable stage, says Mark Hauber, a behavioral ecologist at the University of Auckland, New Zealand: "This is the first example of a bird in which imprinting is not even theoretically feasible."
