We compared migrant bird recapture rate, stopover time, mass gain, and fat class between Star Island, New Hampshire and Appledore Island, Maine during spring and fall migration in relation to differences in relative species abundance between the islands; and examined potential movement of migrants between the islands. The average recapture rate in spring was 5.7% on Star Island and 3.6% on Appledore Island. Five species were recaptured more frequently on Star Island and one species more frequently on Appledore Island. There was no difference in mean minimum stopover time during spring (2.4 days on Star Island; 2.5 days on Appledore Island) and fall (2.9 days on Star Island; 3.2 days on Appledore Island). Three species had a longer mean stopover time on Appledore Island than Star Island. The island with the greater percentage of recaptures and longer stopover had more captures for a given species. Mass gains were significant for six species during spring (27.3%) and 10 during fall (38.5%) on Star Island, and five (22.7%) during spring and 13 (50.0%) during fall on Appledore Island. Five species had a difference in rate of mass gain between the islands. The between-island difference in species abundance was not reflected in between-island differences in mass gain, except for Red-eyed Vireo (Vireo olivaceus) during fall. There was no clear pattern in species differences in fat levels and differences in captures, stopover length, or mass gain between the islands. The fat-class and mass-gain results suggest habitat use, as measured by relative abundance, is not based on the ability to gain mass at the time of stopover. The notable fall mass gains for Red-eyed Vireo illustrate the availability of food resources for some species on both islands. Only 42 of 10,437 migrant birds banded moved from one island to the other. There was little evidence of movement between islands in a seasonally-appropriate direction for continued migration, or evidence indicating a shift between islands after initial capture.

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