Swimming white-beaked dolphins can be most readily identified by the two areas of pale coloration on the sides, one in front of and another below and behind the dorsal fin. These areas are clearly visible from a ship or aircraft as the animals roll at the surface.
Natural History Notes
White-beaked dolphins may sometimes occur in herds of up to 1,500 individuals. Like their cousins, the Atlantic white-sided dolphins, they do not commonly ride the bow waves of vessels.
White-beaked dolphins feed on squid, octopus, cod, herring, capelin, and sometimes on benthic crustaceans.
May Be Confused With
In their northerly range white-beaked dolphins are likely to be confused with only the Atlantic white-sided dolphins. The most distinctive features of white-beaked dolphins are 1) the two areas of paleness described above, 2) the prominent, dark gray dorsal fin, and sometimes 3) the white beak. Other features by which the two species may be distinguished in the brief encounters typical at sea are tabularized on p. [127].
Distribution
White-beaked dolphins are the more northerly of the two species of Lagenorhynchus in the western North Atlantic. They are found from Cape Cod, Mass., north to western and southern Greenland and Davis Straits, though they are apparently far more numerous to the north of this range. They appear in Davis Straits in spring and summer and leave that area in autumn, sometimes as late as November, to move southward. They winter as far south as Cape Cod, where they are the common dolphin species in April, May, and June (sometimes to July). Their migrations are poorly known.
Stranded Specimens
Stranded white-beaked dolphins can be most readily distinguished from white-sided dolphins by the substantial differences in coloration and the differences in numbers of teeth.