If you stand on one of Australia’s southern shorelines at this time of the year, you might be lucky enough to spot a southern right whale (Eubalaena australis) swimming in the shallow waters.

These ocean giants have migrated from the Southern Ocean and Antarctica to breed, give birth and to rest. If you’re really lucky, you may even see one of them resting upside-down.

At first glance, this perplexing behaviour, which has not been reported in other large whales, may make you think the animal is sick or injured. But our new paper, published in the journal Mammalian Biology, suggests quite the opposite.

It may actually be an indicator of a healthy mother carefully managing her energy reserves during one of the most energetically demanding periods of her life.

Southern right whales migrate long distances, greater than 6,000 kilometres. That’s like travelling the distance from Perth to Sydney … and back.

If that didn’t sound difficult enough, southern right whales are not feeding when they are on the calving grounds in Australia. The whales are known as capital breeders, meaning they feed........

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