Pink-footed Shearwater
Ardenna creatopus
Male pink-footed shearwaters on average are found to be larger than females. However, morphological features such as bill size, tail length, head length, and average body size are found to be linked not only to sex, but to breeding locality. These difference may represent adaptations to environmental conditions such as food availability, prey type/mobility and wind speed. In procellariiformes, larger wing area is generally associated with feeding on highly mobile prey, lower wind speeds, and less abundant more dispersed food sources.
ID text from Wikipedia, CC BY-SA 4.0
Wedge-tailed Shearwater
Ardenna pacifica
The wedge-tailed shearwater is the largest of the tropical shearwaters. The two colour morphs of the species are dark and pale; the pale morphs predominate in the North Pacific, the dark morph elsewhere. However, both morphs exist in all populations, and bear no relation to sex or breeding condition. The pale morph has grey-brown plumage on the back, head, and upper wing, and whiter plumage below. The darker morph has the same dark grey-brown plumage over the whole body. The species' common name is derived from the large, wedge-shaped tail, which may help the species glide.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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Play today's Daily BirdPhotos and recordings are credited to their authors under the licence shown. Full profiles: Pink-footed Shearwater and Wedge-tailed Shearwater.