Basking sharks are highly migratory. Off the Atlantic coast of North America, it appears in the southern part of its range (North Carolina to New York) in the spring, shifts northward (New England and Canada) in the summer, and disappears in autumn and winter. Off the southwest coast of the United Kingdom, in the northeast Atlantic, the basking shark feeds at the surface of coastal waters during the summer. These sharks are absent from November to March, suggesting a migration beyond the continental shelf during the winter months. This is explained by the high amount of zooplankton (the main food of the basking shark) that exists in these waters during late spring and early summer. During migration, basking sharks form groups depending on size and gender.