A small wild parakeet has a call that belongs to it alone, and it does not come with the egg. Its chicks pick it up from their parents, then make it their own.
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Researchers studied green-rumped parrotlets in the wild in Venezuela. To separate the role of genes from the role of learning, they swapped eggs between nests. The result: chicks raised by foster parents adopted contact calls very close to those of their new parents.
Adults start producing their contact call when the chicks are still very young. The chick copies this model, then adds small variations of its own, so each one sounds slightly different from its siblings. Some researchers read the parents' calls as a way of identifying each chick before it vocalises itself, although this idea is still debated.
Still, caution is needed. This study covers one species in one population. In other wild parrots, the vocal signature may change over the weeks.
