Telemetric studies have shown that juvenile Streaked Shearwaters Calonectris leucomelas from a colony in the north of Honshu Island, Japan, take a different route from adults during their first southward migration. Juveniles orientate south, resulting in an overland crossing that includes mountains. Adults travel over water, around the land mass. Experience thus seems to modify an innate tendency to migrate south, so that birds remain in contact with the marine environment#R.
Grebes (order Podicipediformes) are unique among birds in the habit of eating their own feathers and later casting them in pellets. Why they do this has been the subject of controversial speculation for centuries. Suggestions include: 1) protection of the digestive tract; 2) enabling pellet formation; 3) guarding against or reducing parasites; 4) aiding digestion. Observations of the Black-necked or Eared Grebe (Podiceps nigricollis) in western North America suggest that the last of these may be the best explanation#R. Feather-eating may assist these birds to exploit abundant tiny aquatic invertebrates, such as brine shrimp, that can be hard to digest.