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
Storrs L. Olson world's foremost paleornithologists. He was also the 1994 recipient of the Loye and Alden Miller Research Award. He was formerly curator of birds at the United States National Museum of Natural History; , he holds an emeritus position in the institution. Several prehistoric bird species have been named after Olson, including "Nycticorax olsoni", "Himantopus olsoni", "Puffinus olsoni", "Primobucco olsoni", "Gallirallus storrsolsoni", and "Quercypodargus olsoni". Storrs L. Olson Storrs Lovejoy Olson (born April 3, 1944) is an American biologist and ornithologist who spent his career the Smithsonian Institution, retiring in 2008. One of the world's foremost avian paleontologists, he is best