Distribution of feather molt for each individual Loggerhead Shrike sampled according to the isotopic criteria: breeding grounds (less than −90‰), or nonbreeding areas (greater than −90‰). Feathers P1, P3, P6, and P9 refer to primary feathers 1, 3, 6, and 9. Feathers S1, S3, and S6 refer to secondary feathers 1, 3, and 6. Feather S9 refers to the innermost tertial feather. Feathers R1, R3, and R6 refer to rectrices 1, 3, and 6 (Fig. 2). Adult Loggerhead Shrikes initiated their flight-feather molt with P1 on the breeding grounds, but molt was not completed prior to fall migration. Following some partial primary replacement, molt was completed on the wintering or more southerly molting grounds.
Distribution of feather molt for each individual Loggerhead Shrike sampled according to the isotopic criteria: breeding grounds (less than −90‰), or nonbreeding areas (greater than −90‰). Feathers P1, P3, P6, and P9 refer to primary feathers 1, 3, 6, and 9. Feathers S1, S3, and S6 refer to secondary feathers 1, 3, and 6. Feather S9 refers to the innermost tertial feather. Feathers R1, R3, and R6 refer to rectrices 1, 3, and 6 (Fig. 2). Adult Loggerhead Shrikes initiated their flight-feather molt with P1 on the breeding grounds, but molt was not completed prior to fall migration. Following some partial primary replacement, molt was completed on the wintering or more southerly molting grounds.
