A dialect or folk name for a type of duck or waterfowl, possibly the pintail or another dabbling duck with a pale or yellowish bill.
From butter (pale yellow) plus bill (the bird's beak). This is a descriptive folk name, common in English regional ornithology where birds were named by their most obvious features.
Butterbill is one of hundreds of regional bird nicknames that rarely appear in field guides—many are disappearing as standardized ornithological terms replace folk knowledge, yet these names often beautifully capture what birds actually look like to ordinary observers.
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