Morphometric sexing of Northwest Atlantic Roseate Terns

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A difficulty in the study of monomorphic species is the inability of observers to visually distinguish females from males. Based on a sample of 745 known-sex birds nesting at Bird Island, MA, USA, a discriminant function analysis (DFA) was used to sex Roseate Terns (Sterna dougallii) of the Northwest Atlantic population using morphological measurements. DFA using only the total length of the head (including the bill) correctly identified the sex of approximately 86% of the terns, which increased to 88% if both members of a pair were measured. Including additional measurements increased these percentages slightly, to 87% and 90%, respectively. These levels of accuracy are generally higher than those reported for other species of terns. Because female-female pairs are frequent in this population, one cannot assume that the member of a pair with the larger head is a male, and additional discriminant functions were developed to help separate female-female from male-female pairs.

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Publication type Article
Publication Subtype Journal Article
Title Morphometric sexing of Northwest Atlantic Roseate Terns
Series title Waterbirds
DOI 10.1675/063.035.0312
Volume 35
Issue 3
Year Published 2012
Language English
Publisher The Waterbird Society
Publisher location Waco, Texas
Contributing office(s) Patuxent Wildlife Research Center
Description 6 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Waterbirds
First page 479
Last page 484
Country United States
State Massachusetts
Other Geospatial Bird Island
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