| Long: when decidedly longer than the trunk, as in a Black-billed Magpie. |
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| Short: when either approximately the length of, or shorter than, the trunk, as in a Least Sandpiper |
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| Square: the retrices are all of the same length, as in
the
Sharp-shinned Hawk. |
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| Rounded: the retrices shorten successively from the inside to the outside, in slight gradations, as in a Red-tailed Hawk. |
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| Graduated: the retrices shorten successively from the inside to the outside, in abrupt gradations, as in a Yellow-billed Cuckoo (a painting by John James Audubon) |
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| Pointed, or acute: the middle retrices are much longer than the others, as in the Ring-necked Pheasant. |
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| Emarginate: the retrices increase in length successively from the middle to the outermost pair, in slight gradations, as in a finch. |
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| Forked: the retrices increase in length successively from the middle to the outermost pair, in abrupt gradations, as in a tern. |
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