What measurable features are generally longer in breeding male Willow Flycatchers than females?
Answer
wings and tails
Although visually similar in the field, ornithological examination reveals slight, measurable differences between the sexes when specimens are handled. Breeding males typically exhibit subtle advantages in certain dimensions compared to females. Specifically, males generally possess slightly longer wings and tails. Additionally, males tend to have longer and narrower bills than their female counterparts. A southern Michigan study illustrated this, showing males averaged a longer wing chord (70.55 mm vs. 67.01 mm) and a significantly longer tail (59.01 mm vs. 52.27 mm).
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