In the “Observation Fields” section of an observation, it offers Plumage Season with a dropdown menu showing four options:
For the very few people who may use this feature, I think ‘basic’ and ‘alternative’ should be added, according to what some ornithologists use today. An example of why it be may be useful. A Franklin’s Gull has two plumages, the one with the black hood being the summer or breeding plumage and the white head being vice versa. However, Franklin’s Gulls, and many other gull species mostly hooded, enter the “breeding” plumage as early as January but molt by early summer. That’s why some ornithologists use the term ‘basic’ for non-breeding and ‘alternative’ for breeding, since these gulls don’t have the ‘breeding’ plumage throughout the entire breeding season.