North American Ornithological Atlas Committee Breeding CodesStandardized Breeding Evidence Codes: 2026 Revision Code CheckA guide to every code for every species

Code Check

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About Code Check

Code Check is a field reference for observers participating in the Breeding Bird Atlases. It helps you quickly assess whether a given breeding behavior code is appropriate for the species you are observing.

Select a species from the list to see all 22 breeding codes color-coded by acceptability:

Acceptable. This code is appropriate to use for the species.

Use with caution. The code is potentially acceptable but is rarely applicable or is often misapplied for this species. Tap for guidance.

Not acceptable. This code conflicts with the species' known biology and should not be used. Tap to see why.

A colored dot in the corner of a code card indicates a note is available. Tap any card for details.

The underlying database of species, codes, and acceptability scores that powers this tool has been collaboratively developed and refined by members of the North American Ornithological Atlas Committee's (NORAC) Breeding Codes working group. Versions of this database were initially developed for a subset of species by the coordinators of individual atlases, including California, New York, Maryland, Ontario, and Wisconsin.

The web tool was developed and is maintained by Sam Safran (✉) for the California Bird Atlas.