Audubon's shearwater underparts are white, as is the head below eye level. The iris is dark, the feet are dull pink with a black wash and black toenails, and the bill is grey, darker towards the tip, and with a pinkish hue. Males and females look alike. Immature birds do not have a distinct plumage, while the nestlings are covered with down feathers, grey above and whitish on the belly. It can be confused with the Manx shearwater ("P. puffinus"), which has white undertail coverts and in direct comparison a longer bill. Other similar-looking species are usually completely allopatric, though the largely
Puffinus and often give eerie contact calls on their night-time visits. They lay a single white egg. They feed on fish, squid and similar oceanic food. Some will follow fishing boats to take scraps, notably the sooty shearwater; these species also commonly follow whales to feed on fish disturbed by them. Traditionally, "Puffinus" has been grouped with the "Procellaria" and "Calonectris" shearwaters. However, more recent results have determined that the genus is apparently paraphyletic and while in part very close to "Calonectris", forms a clade with the genera "Pseudobulweria" and "Lugensa", which were formerly presumed to be gadfly petrels, and can