Yesterday, Kelly and I spotted #1701 and her 2010 calf. (Click here to look up #1701 in the North Atlantic Right Whale Catalog.) While mom was taking relatively long dives (about 10 minutes or so), the calf remained at the surface displaying head lifting, rolling, and tail slashing behaviors. The rolling behavior in particular provided us with some important information — #1701’s calf is male! See the photo of the calf below.



Many cetacean species are only slightly sexually dimorphic (oftentimes just a slight difference in size), so it’s nearly impossible to determine gender in the field. However, if you’re fortunate enough to see an animal roll over at the surface of the water, gender can be determined with the click of the camera. If an animal’s ventral side is exposed, the presence of genital slits can be determined. After reviewing the photos taken from the plane, we were able to determine that #1701’s calf is indeed male.

Gender of individuals in a population, especially one that is as critically endangered as the North Atlantic right whale population, is an extremely important demographic characteristic to monitor. A species needs an appropriate adult sex-ratio that fits their social system in order to ensure reproductive success. Reproductive success depends on many factors – sex-ratio being just one of these factors. Just by determining #1701’s 2010 calf’s gender, this will ultimately help with future conservation efforts for the entire population!

-Karen