Humpback whales favor older males as populations rebound

A study of humpbacks breeding around New Caledonia found that as populations recovered, females increasingly favored older males, who generally sang more elaborate songs; researchers reached this conclusion using genetic analysis of skin samples and song observations.

Researchers followed humpback whales breeding around New Caledonia and report that female mate choice changed as whale numbers grew. Whaling in the 20th century reduced global humpback numbers by as much as 95 percent from an estimated 120,000, and protections since 1986 have allowed many populations to rebound. In the early years of recovery older males were scarce, but over decades younger whales aged and older males became more common. The new study links older males’ greater mating success to differences in singing and was based on genetic sampling and observational data. Key findings: - As humpback numbers increased around New Caledonia, female whales became more selective and favored older males. - Researchers collected skin samples from hundreds of whales and used genetic analysis to estimate age and identify parent-offspring relationships. - Older males tended to be the better performers of the long, elaborate songs males use and which can last for hours and be heard over long distances. - Whales have not been observed mating in the wild, which historically made linking males to offspring difficult until genetic methods were applied. - The study was published in Current Biology and its lead author, Franca Eichenberger of the University of St Andrews, emphasized that recovering populations offer a chance to learn more about humpback behavior. Summary: The study suggests that mate choice in humpback whales is influenced by male age and song performance, with older males more often siring young as populations rebound. Researchers note that continued study of recovering populations and new scientific tools will help clarify humpback life history and behavior in coming years.