by Tom Aversa

revised by Ryan Merrill

Included here are all the species of annual occurrence in Washington—i.e., rare or better as determined by the abundance definitions below. Westside (W) and Eastside (E) have separate graphs if status differs; otherwise they are combined (WE). The Cascade Crest is the division. Species graphed on one side of the state but not on the other are no more than Accidental in occurrence on the side where they are not graphed—i.e., a species must attain the frequency of Casual or better on a second side of the state in order to be graphed there. The status of all species recorded in the state, graphed or not, is discussed in the Annotated Checklist. The status of each species has been updated as needed from the first edition of this guide  to reflect changes during the past decade.

Most species have pronounced habitat associations; some occur quite locally. For example, Black Oystercatcher is shown as Uncommon in Western Washington but in fact can be found only along rocky saltwater shorelines. For a more complete picture, the bar graphs should be used in conjunction with the Annotated Checklist. These two sections were reviewed and revised conjointly, and complement one another. A primary source of information in the preparation of both has been the database of records maintained since 1993 by the Washington Field Notes compilers (Russell Rogers, succeeded in 2001 by Tom Aversa, and in 2009 by Ryan Merrill), derived from reports submitted to them by field observers.

Abundance definitions strike a balance between the probability of finding (seeing or hearing) the bird and its actual abundance. Certain retiring species or those in hard-to-cover habitats may be numerically more abundant yet more difficult to detect than certain other, numerically scarcer ones with exhibitionist tendencies, or that frequent exposed habitats.

In 2000, ABA’s Checklist Committee drafted a set of standard definitions for the bar graphs used in the ABA Birdfinding Guide series. Their aim was to create a set of sensible, easily understandable definitions for the terminology used to denote the abundance and findability of birds, which would be useful not only within ABA, but also for the birding community continent-wide. It is ABA’s hope that, over time, those persons or groups publishing field checklists, annotated checklists, and other compilations dealing with abundance of bird species will adopt these definitions. When standardized terms gain widespread acceptance, disparities between the various meanings of terms such as fairly common and casual will disappear, giving birders a realistic understanding of a species’ actual abundance as well as a good idea of how likely finding it might be. ABA encourages widespread adoption of these abundance definitions; no specific permission is necessary.

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