Assertion: mallard's patch | /r/Synonym | speculum
Facets:
Source sentences:
text: Male and female alike have a bright blue patch, known as a speculum, on each wing.
text: The wing patch (speculum) and the tail was also like in mallard drakes' nuptial plumage, including curled-up central tail feathers, but the tips of the speculum feathers were buff.
text: Male and female alike have a bright blue patch, known as a speculum, on each wing.
text: This blue patch is known as speculum, and it is most visible in flight.
text: These patches are known as “speculums.