Unique mid-tract loss of a primary remex in male broadbills of the Southeast Asian genus Calyptomena: timing and possible implications


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Female Calyptomena broadbills have 10 large primaries, whereas adult males have nine. At or before the main post-juvenile moult, males abort what appears to be juvenile P5. This creation of row space is accompanied by a shortening of the wing tip, a development (together with tail shortening) that, as in some Neotropical suboscines, may relate to performance of exaggerated displays. Calyptomena has been linked taxonomically with Afrotropical Smithornis, the one genus of broadbills with proven display-related modification of flight-feathers.