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on mis-aging and mis-sexing birds in eBird (and elsewhere)

5:24 pm

Fall has arrived and so have a few perennial errors in eBird submissions with the mis-aging and mis-sexing of a number of species. Well, actually this is a definite year-round problem continent-wide, but the examples below are mostly unique to fall and winter. Lately, the appearance of multiple Painted Redstarts has brought also a fair number of submissions stating that a particular individual is a “male,” or an “adult,” or an “adult male.” Essentially all Painted Redstarts look the same after they molt out of juvenal plumage on the breeding grounds. They can’t be easily aged and sexed (if not singing). And there is also now the yearly over-reporting of “female” Black-and-white Warblers because the birds have white throats. But most males lose their black throats in fall and winter, and sexing this species at this time of year should be done on the basis of the auricular/cheek color and secondarily on the flank color and boldness of the side and undertail-covert streaking. Soon, there will probably be reports of “adult male” Black-throated Blue Warblers and Hooded Warblers, despite the fact that young males are essentially identical to adults.
A large percent of eBird reviewers simply do not check age and sex designations, if made, due to lack of time. Or even if they see such an error, they sometimes do not wish to spend the time contacting the observer to get them to change it. Thus many, many incorrect designations fall through the cracks. As a result, I would wager that the overall eBird database has only limited value in this regard, given the large number of incorrectly aged and sexed birds it contains. It is fine NOT to make such designations unless one is truly certain, or perhaps only after consulting the literature and on-line sources to double-check before submitting.
–Paul Lehman, San Diego