LARGE-SCALE PATTERNS OF MOLT ACTIVATION IN THE FLIGHT FEATHERS OF TWO ALBATROSS SPECIES

Abstract

Abstract Laysan Albatross (Phoebastria immutabilis) and the closely-related Black-footed Albatross (P. nigripes) replace 20%–90% of their 35–41 wing flight feathers every year. Large-scale molt patterns (patterns between rather than within molt series) account for 77% of the variation in the number of flight feathers replaced. We identified four molt series: series A—the five outer primaries; series B—the five inner primaries plus four outer secondaries; series C—the middle secondaries; and series D—the inner secondaries. A fifth molt series may lie between series C and D. Each year, series A and D initiate molt, but series B and C may or may not initiate molt. The result is four “annual molt patterns”: ABCD, ABD, ACD, and AD. Temporally overlapping waves of molt never occur within series A or B, but about one third of the time they occur within series C and D. Multiple, spatially defined waves of molt (replaced feathers separated by unreplaced feathers) never occur within series A, but occur about two th...