Other species such as the auks are equally dependent on cliff-ledge breeding sites and marine prey, but tend to be more coastal once they have migrated from their breeding stacks.
Some of the less oceanic species, like grebes and divers, breed in freshwater environments but move to the coasts in winter. A few, such as the Great Crested Grebe and the Anhinga, will also winter on freshwater lakes where they remain unfrozen.
The following are the groups of birds normally classed as seabirds.
Sphenisciformes (Antarctic and southern waters; 16 species)
Pelecaniformes (Worldwide; 57 species)
Sometimes the phalaropes are included in the seabirds, since although they are waders ("shorebirds" in North America), two of the three species are oceanic outside the breeding season.
Although there are a number of sea ducks in the family Anatidae which are truly marine, by convention they are usually excluded from the seabird grouping.
See also list of birds.