Abundance Code represents the number of estimated breeding pairs in a surveyed block:
- 1 breeding pair
- 2-10 breeding pairs
- 11-100 breeding pairs
- 101-1000 breeding pairs
- more than 1000 pairs
Abundance was desirable (although optional) for atlasers to record. In order
for atlasers to estimate total number of breeding pairs in a given block, they
were to determine how much suitable breeding habitat was in the block for a given
species and extrapolate from the number of breeding pairs in the surveyed portions
of the block.
Abundance code was not necessary for observations with a breeding code of just
Observed (O). | 
