Molt is a critical part of every bird’s life history, but there is a limit to the rate feathers can grow, which is about 4 to 10 mm/day in large birds (Prevost 1983). Hence some large and long-winged birds may have insufficient time between breeding seasons for a complete molt of their wing feathers, particularly the primaries (Langston and Rohwer 1996, Rohwer 1999). Molt of the primaries in most birds is sequential, from the innermost (primary 1, or p1) out to the outermost (usually p10), but some variations on this theme have developed in long-winged birds, so that they can fly more efficiently during molt. For example, the molt of albatrosses involves splitting the primaries into series. In the Black-browed (Thalassarche melanophris) and Gray-headed (T. chrysostoma) albatrosses, the outer three primaries are molted every other year, and some inner and middle primaries are molted every year (Prince et al. 1993). In the Black-footed (Phoebastria nigripes) and Laysan (P. immutabilis) albatrosses, the outer three primaries are usually molted every year, along with no to all inner and middle primaries (Langston and Rohwer 1995; pers. obs.). Year-to-year differences in the extent of primary molt reflect combinations of variation in the bird’s age, breeding status, and food supply (Prince et al. 1993; Table 1).