Groups of several thousand form during pupping and mating season. Baikal seals mate in the water towards the end of the pupping season. It shelters the largest rookery of breeding and pupping harbor seals on the north coast. About 1,000 harbor seals depend upon the island for a pupping and rest area. Grey seals use the island as a pupping site. It is possible that they come to inshore pupping grounds to give birth. Massachusetts is the southernmost point of known pupping areas along the Atlantic Coast. The southern Gulf of California appears to be an important mating and pupping ground. The pupping grounds are in coastal and estuarine waters. In the Canadian Arctic, seal pupping occurs in May. Plants bloom from 30 years old on, with prolific pupping prior to dying post flowering. Their pupping grounds are off the coast of South Carolina. These caves house breeding colonies for Townsend's big-eared bat and are closed during pupping season. Pupping season is officially mid-January to mid-April. The grey seal colony at Donna Nook in Lincolnshire was inundated during pupping season.