Scientists found that blue whale calves are rarely seen because research happens in summer, but calves are born in winter.

Only two blue whale births have ever been recorded in human history, both decades ago. This remains an extraordinary mystery, given there used to be hundreds of thousands of blue whales before whaling started—even today,

Blue whales might be some of the most iconic creatures on the planet, but for all their impressive features, there’s still plenty we don’t know about them. One particularly confounding mystery is why their calves are so rarely seen – but a new study has come up with an interesting proposal as to why.