The narwhal whale is able to produce a calf once every 3 years with a 15-month gestation period. Newborn calves are dark blue-gray, but as they mature the back transforms to an olive brown and begin to develop the spotting which is most often seen in adults narwhals.
Narwhals calves are usually born in July and are rarely born outside deep bays and inlets and remain with the female narwhal for up to twenty months after they are born.
As adults the calves can grow to become 4.6 meters and weigh up to 1600 kilograms, if male. The female of the species can grow up to 4 meters and weigh up to 1000 kilograms.