We examined brood patch development, sex ratios, and morphological traits of 30 Ancient Murrelets Synthliboramphus antiquus captured from the nocturnal at-sea congregation off Teuri Island, Hokkaido, Japan during late May to early June 2016. Molecular sexing determined that 12 of the murrelets were males and 18 were females. The proportions of murrelets with brood patches (an indicator of breeding status) were similar for males (58%) and females (56%). Breeding murrelets were heavier than non-breeding murrelets. Males had deeper bills and longer heads than females, but their weights, wings, culmens, tarsi, bill widths, and skull widths were similar.
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24 July 2020
Breeding Status and Sex Ratio of Ancient Murrelets Captured in the Nocturnal At-Sea Congregation Off Teuri Island, Japan
Shin Matsui,
Darrell Whitworth,
Norimasa Sugita,
Isao Nishiumi
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Ornithological Science
Vol. 19 • No. 2
July 2020
Vol. 19 • No. 2
July 2020
At-sea congregation
Breeding season
brood patch
Night-lighting capture
Synthliboramphus antiquus