This is a graphic that illustrates molt sequence of the sanderling. Although this is a shorebird, this sequence is typical of many birds that have a basic and an alternate plumage. Pre-alternate molts are usually incomplete, while the pre-basic molt typically results in a bird replacing all of its feathers. Instead of a normal pre-basic molt, juvenal birds go through a pre-formative molt, which is incomplete and a bird won’t replace all of its juvenal feathers until its first pre-basic molt.
ScienceDaily (Dec. 2, 2011) — When it comes to choosing their wintering destinations Antarctic skuas are flexible. This is shown in a study of an international research team led by the polar-ornithologist Dr. Hans-Ulrich Peter from the Friedrich Schiller University Jena (Germany). According to the study, a great part of the South Polar skuas spend the Antarctic winter in the Northern Atlantic. At the same time about one third of the same species overwinters in the Northern Pacific, tens of thousands of miles away.