Right whale calves can measure 13-15 feet and weigh 2,000 pounds
DNR’s marine mammal staff and Clearwater Marine Aquarium Research Institute aerial survey teams sailed into the calving season for North Atlantic right whales last month, encountering mom-calf pairs of these endangered giants off Georgia’s coast. Those encounters might have you wondering how we estimate the age of right whale calves.
Video of Juno and calf (DNR/NOAA permit 26919)
The gold standard, of course, is seeing an adult female one day without a calf and seeing her again a few days later with one. Above is drone footage of Juno (right whale catalog no. 1612) and her calf about 7 miles off Sapelo Island on Dec. 4.
Born after Juno was first documented in the Southeast this season — alone Nov. 24 off North Carolina — the calf was 1-5 days old when spotted off South Carolina on Nov. 28 and 7-11 days old at the time of this video. (Tip: Watch until the end to see Sapelo in the distance.)
But beyond spotting a mom sans calf and shortly afterward confirming that she’s trailing a newborn, we can determine the approximate age of calves through a combination of physical and behavioral characteristics. These include:
- Fetal folds on the calf (creases in the skin and blubber from the calf’s position when it was in the uterus).
- Fewer cyamids on the head or lip margins.
- Floppy fluke tips.
- Raised or “periscoped” blowholes.
- Thin, tubular body shape.
- Movements that appear clumsy and uncoordinated.
- Frequent respirations.
- Apparent inability to submerge for long periods.
To help illustrate the age-identifying aspects, here are photos of a calf from right whale no. 4094 in 2016. Although the age of this calf was known (the mom was seen the day before without it), having a better grasp of characteristics exhibited by a calf whose age has been documented help us more accurately assess those whose age hasn’t been.
Top image: Note the periscoped blowhole. Middle: Fetal folds are very evident on the body. Bottom: The calf’s body is thin and tubular-shaped. Also, the calf’s swimming and diving were uncoordinated, its fluke tips were floppy and respirations were frequent. (NMFS Marine Mammal Health and Stranding Response Program and DNR/NOAA permits 18786 and 15488)
And for comparison, here are photos by boat and plane of the same calf at 12 days old. We would still consider the calf a neonate, but the changes are noticeable.
Top image: The blowholes still appear periscoped (the calf also was breathing frequently). Middle, bottom: Although the fluke tips are still floppy, the calf’s body shape is less tubular, the fetal folds are no longer visible, cyamids (whale lice) are visible on the head and the nuchal, or nape of the neck, region is more convex. The calf’s swimming also was well‐coordinated. (NMFS Marine Mammal Health and Stranding Response Program and DNR/NOAA permits 14450‐04 and 15488)
Stay tuned as we continue to provide updates on this right whale calving season.
(Note: It is illegal to approach right whales in U.S. waters without a research permit. Other vessels, aircraft and drones must maintain a distance of at least 500 yards from these endangered whales. Researchers shown have the training and permits required to approach right whales safely and legally.)