A recent study led by researcher Alexandra Childs has shed light on the surprising behavior of fully grown Galápagos Islands sea lions that continue to nurse from their mothers well into adulthood. Childs, a PhD candidate in behavioral and marine biology at the University of Bielefeld in Germany, expressed astonishment at this phenomenon, emphasizing the unexpected nature of the discovery.
The study, published in the American Naturalist journal, revealed that approximately 11% of the sea lion population in the Galápagos exhibit prolonged nursing behavior, termed as “supersucklers.” Childs likened this behavior to humans breastfeeding into their teens and 20s, highlighting the mystery surrounding why mothers allow such extended nursing despite the offspring’s ability to hunt independently.
Analyzing two decades of data on Galápagos sea lions (scientifically known as Zalophus wollebaeki), the study found that while most sea lions wean from their mothers between 1.5 and 4.5 years of age, the supersucklers continue nursing well beyond this typical age range. The research documented instances of multigenerational suckling trains, where multiple sea lions engage in nursing behaviors simultaneously.
Although similar behaviors have been observed in other sea lion species and seals, the frequency and extent of supersuckling in Galápagos sea lions stand out. Researchers suggest that this behavior may be linked to food availability, as supersuckling was more common during periods of abundant food resources. Further research is needed to fully understand the underlying reasons for this unique behavior among Galápagos sea lions.
Despite the intriguing findings, experts emphasize the complexity of factors influencing food availability and the need for comprehensive studies to gain deeper insights into the ecological and biological implications of supersuckling in sea lions.
