13.10.2025 – The grandmother effect

Today was a day full of Sperm whales (Physeter macrocephalus) and Short-finned pilot whales (Globicephala macrorhynchus)! Here’s an interesting fact about them: the grandmother effect!

The so-called grandmother effect describes the phenomenon in which older, no longer reproductive females increase the survival chances of their offspring and grandchildren through their experience and support. This behavior is well documented in humans, but it also occurs in some whale species—particularly in Sperm whales and Short-finned pilot whales and Orcas.

In these species, females go through a kind of menopause, meaning they stop reproducing long before they die. Instead, they take on important social and ecological roles within the group. Older females possess decades of experience in finding food, navigating vast ocean areas, and assessing dangers. They pass this valuable knowledge on to younger group members.

Among Sperm whales, females form stable matrilines, usually consisting of mothers, daughters, and their offspring. Grandmothers help protect and care for the calves, especially when the mothers dive deep to hunt squid. Their presence has been shown to significantly increase the survival rate of the young.

A similar effect has been observed in Pilot whales. Older females take on leadership roles, guiding the groups to productive feeding grounds and maintaining social stability. Research shows that groups lacking experienced older females are more prone to navigation errors and food shortages.

The grandmother effect in these whales suggests that menopause did not arise by chance in evolution but provides a clear survival advantage. Through the transfer of knowledge and care, grandmothers help ensure the family’s survival—an impressive example of social intelligence and intergenerational cooperation in the animal kingdom.

By Fatima Kutzschbach

Sightings of the day

Ribeira Brava

09:00 Sperm whales, Pilot whales

13:00 Sperm whales, Pilot whales, Bottlenose dolphins

Stenella

09:30 Sperm whales, Pilot whales, Bottlenose dolphins

13:30 Sperm whales, Pilot whales, Bottlenose dolphins

16:30 Pilot whales, Bottlenose dolphins, Atlantic spotted dolphins