Calving

Female narwhals reach sexual maturity between their fifth and eighth years, at a length of 3.9 metres. Males are sexually mature three to five years later, upon reaching a size of 3.4 metres. Upon reaching sexual maturity, females are thought to bear young approximately every three years.

Narwhals are reported to mate belly to belly while vertical underwater. Mating is believed to take place from March to May, with births taking place the following summer after a gestation period of fourteen or fifteen months. Calves tend to stay with their mother for an extended period of time, and it is estimated that they will rely on their motheräs milk for sustenance the first twenty months of their lives.