Over a decade ago, behavioral ecologist Diane Colombelli-Négrel was wiring superb fairy wrens’ nests to record the birds’ sounds when she noticed something odd. Mother fairy wrens sang while incubating their eggs, even though it would have made more sense to keep quiet to avoid attracting predators.
The discovery “was a bit of an accident,” says Colombelli-Négrel, of Flinders University in Adelaide, Australia. And it made her wonder: Could the baby birds be learning sounds, or perhaps even songs, even before they hatch?
The finding is a surprise to many birdsong scientists, says vocal learning neuroscientist Wan-chun Liu of Colgate University in Hamilton, N.Y., who wasn’t involved in the new research. “We used to think a lot of the learning happened after hatching, but now there seems to be more and more evidence suggesting, even in the embryonic stage … they are listening,” he says.
In birds and humans, a drop in embryonic heart rate is known to indicate attention to a stimulus. Colombelli-Négrel and colleagues’ earlier studies of unhatched fairy wrens showed a slowed heart rate in response to repeated sounds of their own species, but not others.
To investigate whether this phenomenon is widespread among birds, the team turned their attention to the embryonic heartbeats of captive Japanese quail (Coturnix japonica domestica), plus three more wild species: little penguins (Eudyptula minor), red-winged fairy wrens (Malurus elegans) and Darwin’s small ground finches (Geospiza fuliginosa).
The team temporarily removed 109 eggs from nests and measured the heart rates of unhatched chicks before, during and after exposure to playbacks of songs from their own species or others. And the researchers investigated whether 138 individual embryos became habituated to repeated sounds of unfamiliar individuals singing their species’ own songs, which would imply learning had occurred.
The discovery “was a bit of an accident,” says Colombelli-Négrel, of Flinders University in Adelaide, Australia. And it made her wonder: Could the baby birds be learning sounds, or perhaps even songs, even before they hatch?
The finding is a surprise to many birdsong scientists, says vocal learning neuroscientist Wan-chun Liu of Colgate University in Hamilton, N.Y., who wasn’t involved in the new research. “We used to think a lot of the learning happened after hatching, but now there seems to be more and more evidence suggesting, even in the embryonic stage … they are listening,” he says.
In birds and humans, a drop in embryonic heart rate is known to indicate attention to a stimulus. Colombelli-Négrel and colleagues’ earlier studies of unhatched fairy wrens showed a slowed heart rate in response to repeated sounds of their own species, but not others.
To investigate whether this phenomenon is widespread among birds, the team turned their attention to the embryonic heartbeats of captive Japanese quail (Coturnix japonica domestica), plus three more wild species: little penguins (Eudyptula minor), red-winged fairy wrens (Malurus elegans) and Darwin’s small ground finches (Geospiza fuliginosa).
The team temporarily removed 109 eggs from nests and measured the heart rates of unhatched chicks before, during and after exposure to playbacks of songs from their own species or others. And the researchers investigated whether 138 individual embryos became habituated to repeated sounds of unfamiliar individuals singing their species’ own songs, which would imply learning had occurred.
