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3. What is meant by ABA countable?

The ABA has a large set of rules for which bird observations are countable. The observer is responsible for interpreting and applying these rules. The way records are coded in birdnotes files tells us these things about observations that are important to the abalist program:

Although the ABA totals are generally referred to as “species totals,” they may include observations pegged to other taxonomic ranks:

It is also of interest to the author which observation was the first for a given species or other taxon. So, after assembling a list of observed taxa, here are the rules for counting the “species” in that list. We step through the list in phylogenetic order and apply these transformations to the tree of observed taxa:

  1. If a form was observed but its parent species was not, promote the observation to the species level.

  2. If a form was observed but its parent species was also observed, retain whichever observation was earlier, and peg it to the species level.

  3. For any taxon at species level and higher, remove all ancestor taxa. For example, if there is an observation pegged to a given species, remove any observation from its containing genus, subfamily, family, etc.

After the tree is transformed by these rules, the number of nodes remanining is the species count for ABA purposes.

Here are some examples. In this table, the left-hand column shows the raw observations, and the right-hand column shows the transformed observation set.

BeforeAfter


1999-12-27 American Green-winged Teal
              


1999-12-27 Green-winged Teal
              


2002-11-22 Snow Goose
2004-01-13 Blue Goose
2003-12-28 white Snow Goose
              


2002-11-22 Snow Goose
              


2004-01-13 Blue Goose
2003-12-28 white Snow Goose
              


2003-12-28 Snow Goose
              


1998-05-10 Aechmophorus sp.
2003-06-07 Western Grebe
2001-08-18 Clark's Grebe                
              


2003-06-07 Western Grebe
2001-08-18 Clark's Grebe                
              

In the first example, American Green-winged Teal is a form of the species Green-winged Teal. Since its parent species is missing, it is promoted to species.

The second example has Snow Goose and two of its forms. Because the species-level observation is first, it takes precedence over its forms.

In the third example, the white Snow Goose record is promoted to species level because it predates the other form.

The fourth example shows genus Aechmophorus and two of its species, Western and Clark's grebes. The genus is deleted because there are records below it.