Date: July 6, 2016
Source: Society for Experimental
Biology
Sleeping king penguins react
differently to the sounds of predators than to non-predators and other sounds,
when they are sleeping on the beach. Research has revealed that even asleep,
these penguins can distinguish between dangerous and benign sounds.
Both adult and juvenile king
penguins are prey to large predators like orcas and giant petrels. Even huge
non-predator elephant seals can crush penguins to death with their bulky
passage. In an environment like this, king penguins who are exhausted after
long diving sessions must constantly keep an ear out for incoming threats.
PhD student Tessa Abigail van
Walsum explains: "When we played single tones to sleeping penguins, they
woke up with little reaction. However, playing them the calls of orcas or skuas
caused them to wake up and flee."
Penguins also had strong
reactions to some non-predator sounds, reports Ms van Walsum: "The sounds
of approaching elephant seals rang big alarm bells for the penguins.
Interestingly too, a recording of simple white noise had an unexpectedly strong
effect, likely because it sounds much like an incoming wave on the beach."
Notably, playing them the sound of unfamiliar predators, such as a dog's growl,
got little reaction when they awoke.
The ability of these birds to
respond differently upon waking up suggests that they might sleep with just one
half of their brain, while keeping close watch with the other half similar to
some migratory birds -- essentially 'keeping an eye open'.
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