What makes correctly identifying female orioles challenging for birders in Wisconsin?

Answer

Both species present in shades of yellowish-olive or dull yellow-green

Distinguishing the females is difficult because both the Orchard and Baltimore Orioles present in similar shades of yellowish-olive or dull yellow-green, requiring close attention to subtle structural differences.

What makes correctly identifying female orioles challenging for birders in Wisconsin?
locationbirdanimalWisconsinoriole