| 11. | Pine siskin in its typical culmen, compare with a short bill in European siskin, with a decurved culmen.
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| 12. | The species has a distinct " even " curvature of its culmen that is not found in any other icterid.
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| 13. | The hard, inflexible culmen, the exposed bill portion as measured along the top of the beak, is only.
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| 14. | Specimens examined by Peter Cotton had an average wing length of 60.5mm and exposed culmen length of 18.5mm.
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| 15. | It is differentiated by the lower breast and abdomen coloration, the male's distinctive growling song, and feathered culmen base.
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| 16. | The bill is yellow with a blue and black line on the culmen and tip, and the feet are greenish-grey.
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| 17. | During the breeding season particularly, the males are characterised by the base of their culmen, which takes on various shades of red.
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| 18. | For example, the culmen of the parrot crossbill is strongly decurved, while that of the very similar red crossbill is more moderately curved.
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| 19. | Among standard measurements, which at average and maximum are greater than any other living owl other than tail length, the culmen is around.
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| 20. | The culmen of a juvenile common loon is all dark, while that of the very similarly plumaged juvenile yellow-billed loon is pale towards the tip.
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