The paper proposes a sequence-based approach to defining moults in migratory birds, emphasizing the fixed nature of feather replacement sequences compared to the more variable timing and location of molts. It argues that this method can clarify moult strategies, especially in species with complex or overlapping molts during non-breeding periods. Examples from North American passerines illustrate how this approach distinguishes between preformative, prebasic, and prealternate molts, even when these overlap temporally.

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This paper presents an interesting perspective on defining molts in migratory birds based on feather replacement sequences. However, the limited quantitative data, overemphasis on feather sequences, and small sample size restrict its overall impact. It provides valuable observations and a framework for future research, but further investigation with larger datasets and more robust analytical methods is needed to validate and generalize the findings.