4ISSF, Audubon's have yellow throat and Myrtle have white while other two are limited to central America. Diagnostic signs of AU or MY are good, as MY is widespread across North America (but dominant in east and Alaska) while AU is more western skewed. Plumage varies, breeding tend to be darker with eye mask and chest patterning that is lost in non-breeding. M/F differ, male is black-grey and female is brown-grey; e.g., a breeding male MY is dark grey while a female is brown.