Orcas are known for their intense mothering duties, enduring one and a half years of pregnancy, followed by up to two years of nursing, and then continuing to provide food and care for their adult offspring throughout their lives. A recent study published in the journal Scientific Reports sheds light on the physical toll this motherhood takes on orca moms.
The research, led by biologist Sharon Kay, focused on northern resident killer whales, a threatened species under Canada’s Species at Risk Act. The study examined the impact of childbirth and nursing on the body fat levels of these ocean mammals. It was discovered that the number of living offspring, rather than the number of births, significantly affects how quickly mothers regain body fat after pregnancy.
To assess the body fat of the killer whales, researchers utilized drones to capture images of the animals from above. By analyzing the pixelated patches above the whales’ eyes, the team could track changes in their body condition. The findings revealed that mothers with more living offspring had lower body fat levels, indicating the prolonged impact of caring for adult children.
Amy Rowley, a biologist with the Raincoast Conservation Foundation and co-author of the study, highlighted the steep decline in fat levels that mothers experience during nursing, lasting up to three years. Some mothers struggle to return to their pre-pregnancy condition due to the ongoing demands of feeding and caring for their offspring.
Experts emphasize the societal pressures faced by these animals, including human-induced threats such as chemical contaminants, noise pollution, and climate change. These additional stressors could further contribute to declines in body fat levels among orcas, potentially jeopardizing their survival.
The study underscores the significance of understanding the maternal investment and challenges that orcas encounter in their environment. By unraveling the complexities of these socially intricate creatures, researchers aim to provide insights that can aid in their conservation and management.