Study Explains Rare Sightings of Blue Whale Calves

Researchers propose that the timing and location of blue whale births explain why mother-calf pairs are rarely observed in the wild.

Blue whale calves are rarely sighted, with mother-calf pairs making up only 3.1% of sightings despite high pregnancy rates of 33-50%.
A University of Washington study suggests that births occur in fall and winter in warmer regions, away from summer feeding grounds where most research is conducted.
Calves are weaned at around seven months of age, before returning to feeding areas, further reducing the likelihood of mother-calf sightings.
Historical whaling records and long-term field studies show higher calf proportions in winter regions and lower proportions in summer feeding areas.
The findings suggest that low calf sighting rates are due to research timing and location, not low birth or survival rates, offering hope for blue whale population health.