Researchers don't know where they went. By May, the whales leave Stellwagen Bank and swim out to feed on the dense copepod patches along the Great South Channel southeast of Cape Cod where they are joined by the majority of the right whale population before heading north. In summer and early fall, approximately two thirds of the mother-calf pairs move into the Bay of Fundy to nurse. Many other whales, both male and female, migrate to the Scotian shelf where they feed and engage in courtship behavior. Approximately half of all known females and three-quarters of all known males have been spotted at least once in this region during the 15 years that researchers have studied the whales.
Researchers also suspect that there is a second summer nursing ground.
Whereas two thirds of all mothers always bring their calves to the Bay of Fundy, many mothers never show up, and researchers don't know where they go. Scientists have determined, based on DNA studies, that females that had been nursed in the Bay of Fundy usually return after their first year and eventually bring their own calves. Females who were not nursed in the Bay of Fundy rarely appear there. Males, on the other hand, only occasionally return to their nursing grounds. But in recent years, for reasons researchers don't understand, a number of males have shifted their summer grounds from the Scotian shelf to the Bay of Fundy.