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5.7. The Census class

Each instance represents one kind of bird seen within a circle-year.

.lat, .lon, .year_no, .year_key

The concatenation of these columns relates each instance to the effort table.


An integer value that orders census records within a year according to their published order.

.form, .rel, .alt_form

These three values identify the type of bird. See Section 3.6, “Kind of bird”. The .form value is always uppercase and right-blank-padded to a length of six. The .rel value is " ", "x", or "/". If the .rel is not blank, the .alt_form attribute is the second bird code, also uppercased and right-blank-padded to six characters.


Age code: " ", "a", or "i".


Sex code: " ", "m", or "f".


Count-week flag: " " or "+".


Questionable status: " " or "q.


Count of birds as an int. The value may be −1 to signify an unknown count. There used to be at least one row in this table that had a zero census, which is an error. (Audubon's database, by contrast, uses zero for count-week birds and never shows a value of −1.)