The Christmas Bird Count is organized by the National Audubon Society. Available bird data for the Christmas Bird Counts obtained from Count Data by areas (by Count Circles):
Count circles are mapped in:
Based on the above map I selected data for the locations included in the
Delta-Suisun Bay/Marsh (the circle code is indicated in the file name,
after the name (e.g. CARC, CASM, CAEC, CABE, CAST).
The attached PDF explains each of the colums in the files.
As you will see data are sporadic but at least give you an idea of
per species per unit of time.