First Quantitative Evidence of Cooperative Birth Assistance in Sperm Whales

A landmark research initiative has published the most comprehensive scientific documentation of a sperm whale birth, providing the first quantitative evidence of cooperative birth assistance among non-primate animals.

The findings are based on integrated audio and visual data collected during a multi-hour event in the Caribbean Sea.

Event Overview and Documentation

On July 8, 2023, researchers from Project CETI (Cetacean Translation Initiative) observed a sperm whale (Physeter macrocephalus) birth off the coast of Dominica. The team documented the event using aerial drones and underwater hydrophones over approximately five and a half hours.

The mother, a 19-year-old female known as "Rounder," was giving birth to her second calf.

The observing scientists noted that direct observations of sperm whale births are rare, with only four reported in scientific literature over the past 60 years. Out of 93 known cetacean species, births have been observed in the wild for only nine.

Key Observations and Behaviors

The research documented the coordinated actions of an 11-whale social unit, which included two typically separate matrilineal family groups.

• Labor and Delivery: The delivery process lasted 34 minutes. During labor, other adult female whales positioned themselves near Rounder, including under her dorsal fin.
• Immediate Post-Birth Activity: Following the tail-first birth, the pod's behavior changed rapidly. Multiple adult females surrounded the mother and newborn.
• Cooperative Calf Support: For approximately one to three hours after the birth, the whales took turns physically supporting the newborn calf. Behaviors included lifting the calf to the surface, pressing its body between theirs, and guiding it through the water.
• Group Cohesion: The entire unit remained in a tight, organized cluster during the supportive period before later dispersing into smaller foraging groups. Brief interactions with Fraser's dolphins and pilot whales were also recorded.

Analysis indicated every member of the 11-whale group participated in supporting the calf at least once, with a core group of four whales providing the majority of the support time.

Scientific Analysis and Findings

The data was analyzed in two separate studies published in the journals Science and Scientific Reports.

• Quantifying Cooperation: One study utilized drone footage, computer vision, and network analysis to quantify caregiving. It reported that female sperm whales from two unrelated matrilines assisted the laboring mother, with both kin and non-kin aiding the newborn. This is cited as the first quantitative evidence of birth attendance outside of humans and some other primates, and of direct allocare (care for non-offspring) in cetaceans.
• Vocalization Shifts: The second study provided a detailed account of the birth and reported distinct shifts in the whales' vocal styles, including slower, longer click sequences, during key events. The specific function of these vocalizations was not determined by the current study.

Context and Implications

• Social Structure: Sperm whales live in matrilineal social units. The observed cooperation involved Rounder's mother, "Lady Oracle," and her daughter, "Accra," representing three generations, as well as unrelated individuals.
• Evolutionary Significance: Phylogenetic analysis referenced in the studies suggests cooperative caregiving during birth may be an ancient behavior, potentially predating the most recent common ancestor of toothed whales by over 36 million years.
• Calf Physiology: Newborn sperm whales are negatively buoyant, lacking a fully developed oil-filled organ, and require assistance to reach the surface to breathe.
• Calf Status: The newborn calf was sighted again on July 25, 2024.

Researchers hypothesize that such transient, highly coordinated cooperation during critical moments may be a key mechanism for sustaining complex sociality in sperm whale societies.

The research was led by scientists from Project CETI, including contributions from the Dominica Sperm Whale Project, which has studied local whale families for over two decades.