Recovery of humpback whale populations shifts reproductive success toward older experienced males

A University of St Andrews study reveals older humpback males are fathering more calves as populations recover, using experience in song and competition.

By: AXL Media

Published: Mar 6, 2026, 6:41 AM EST

Source: The information in this article was sourced from University of St Andrews

Shifting Baselines in Whale Recovery

A study from the University of St Andrews, published in Current Biology, has found that the age dynamics of male humpback whale reproduction have significantly changed as populations recover from near extinction. Commercial whaling once decimated whale numbers, leaving behind a legacy that affected the age structure of surviving groups. In the early stages of recovery, breeding populations were dominated by younger whales. However, as the species continues to rebound, older and more mature males are returning to the breeding grounds in greater numbers, fundamentally altering the competitive landscape for fathering the next generation.

Genetic Paternity and Age Estimation

Because humpback whales have never been observed mating in the wild, scientists utilized advanced genetic tools to uncover reproductive patterns. An international research team, led by the Sea Mammal Research Unit, performed genetic testing on small skin samples to determine the paternity of calves. To accurately assess the age of these free ranging animals, researchers employed an epigenetic molecular clock, which estimates age based on molecular markers in the skin. This dual approach allowed the team to correlate reproductive success with the maturity of individual males over a period of nearly two decades.

Vocal Performance and Competitive Advantage

The research highlights the role of elaborate whale songs and physical competition in the mating process. Male humpback whales produce complex vocalizations to attract females, a skill that appears to improve with age. Senior author Dr. Ellen Garland noted that as the population recovered, older males were observed singing and escorting females more frequently than expected. The findings suggest that it takes years for males to perfect these songs and develop the physical strategies necessary to win intense encounters with rivals. This experience provides older whales with a distinct advantage as the breeding grounds become more crowded and competitive.