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For Humpback Whales, Romance Comes With Age

As humpback whale populations recover, researchers are gaining a richer understanding of these wondrous creatures. A new study reveals it may take years for humpbacks to learn how to successfully serenade a mate.

Before being decimated by whaling a century ago, there were around 120,000 humpbacks globally, but over decades their numbers were reduced by as much as 95 percent. Since countries agreed to ban commercial whaling in 1986, humpback whales have been rebounding and have nearly recovered in some regions.

For a new study, researchers followed humpbacks breeding around New Caledonia, in the South Pacific, where the whales have been rebounding over the last two decades. In the early years of that recovery, older whales were scarce. But over time, young whales aged, and older whales grew more abundant. As the humpbacks recovered, researchers could see that older males were more successful at wooing mates.

Because whales have never been seen mating in the wild, it has been historically challenging to determine which males sire which offspring. For the new study, published in Current Biology, researchers gathered samples of skin from hundreds of whales, using genetic analyses to gauge their age and identify their young.

As for why older whales proved so much more romantically adept, scientists say it may have to do with their singing. Not only do males jostle with each other for the privilege of sidling up to a mate, they also compete by performing elaborate songs. In breeding grounds, males all sing the same song in sessions that can last for hours. The songs, which mirror the structure of human language, can be heard from miles away.

The findings of the new study suggest that it may take years for males to refine their singing skills. In New Caledonia, females came to be more selective as males grew in number, favoring only the best performers, who were generally older.

Researchers say the study highlights the need to continue to study humpback whales as they recover. Most studies of the animals were undertaken after they were nearly wiped out by whaling. It is only now, as humpback numbers grow and new scientific tools become available, that researchers can glimpse the whales in something approaching their natural state.

“Humpback whales have shown a remarkable comeback over recent years,” said lead author Franca Eichenberger, of the University of St Andrews. “Now is the time we can learn so much more about their behavior and life history. We just need to keep looking.”