At the same time that eBird provides lots of useful features to help one chase rare birds (and keep track of one's lists), the system is also intended to accumulate useful data for analyses of trends in bird populations and distribution.  Reflecting that end, the data entry pages include the question "Are you submitting a complete checklist of the birds you were able to identify?"  The answer to this question should serve as a filter for separating checklists intended to add a tick to the observer's personal lists from those that could be taken to represent a survey of the birds present at a given location and date.

As a glance at recent postings from Maryland will indicate, people often answer "yes" but clearly should have picked "no".  For example, many of the reports of the Pink-footed Goose are accompanied by supposedly complete checklists that include zero to a handful of other species.  I do not believe that anyone who successfully (or, actually, even unsuccessfully) chased that bird failed to also identify a Canada Goose at the same location.  (And if an observer cannot identify a Canada Goose, there would be reason to be suspicious of a claimed Pink-footed.)

In the long term, the useful ness of eBird data will depend on people answering this question correctly.

As an aside, I have also seen checklists (e.g., from some California reports) that appear to err in the other direction:  Despite a seemingly complete list of species (with numbers that make sense and even short supporting notes for rarities), the checklist is flagged as incomplete.  

Cheers and good birding.

Sherman

Sherman Suter
Port Republic MD 20676  /  Alexandria VA 22307


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