pycbc: A Python interface to the Christmas Bird Count database

The First Christmas Bird Count was run on Christmas Day in 1900. Later, the count period was extended to allow counts on dates from mid-December through early January.

Each yearly cycle is published separately. We will use the term year number to mean 1 for the first year of the CBC, 2 for the second, and so on. In general, year number N includes dates in December of year 1899+N and January of year 1900+N.