About the County Checklists On This Website

First, a few caveats

The list of species for each of the United States' more than 2,000 counties that you can get on this website is derived from eBird.org, a website of the Cornell University Lab of Ornithology. Many thousands of birders regularly submit their sightings to eBird.org, which makes the information openly available to all.

The resulting vast store of information about which birds are seen when and where provides extremely valuable information to scientists, birders and others. You can see the progress of migration as birds move south to north in the spring and back south in the fall. EBird information can also show the effect of storms on the distribution of birds. It can show the range of a species: where it is regularly seen at various times of the year. And it can reveal declines in abundance of a species. These are just a few examples.

Most states have volunteer committees of experts who determine the official state checklist of birds that have ever been seen in that state. Sightings are rigorously vetted to make sure that the bird was actually correctly identified. Caveat No. 1 is that the eBird checklists are not official state checklists. However, sightings reported to eBird are also vetted. Any sighting that is submitted that is regarded as unusual must be approved by a volunteer recruited by eBird before it will be accepted into the database. This vetting is not as thorough as the official state committees but does ensure a certain standard of quality.

Caveat No. 2 is that not all species that have ever been seen in a state have been entered into the eBird database. A California Condor seen by Lewis and Clark in Washington State in 1805, for example, has not been entered into the eBird database. The eBird database shows 502 species for the state of Washington, whereas the official state checklist (which includes the California Condor) shows 513 species. However, it's likely that the 11 species that are on the official Washington state checklist but not in the eBird database are rare sightings from years ago.

Each year, new rare sightings are reported and accepted by state committees, so checklists do grow. (Sometimes they even shrink as previous sightings records are re-reviewed.) The county checklists shown on this site were based on eBird lists as of April 2018. Any new species reported to eBird after that will not be shown on this website's county checklists, but any such subsequent new species are likely to be rare or uncommon visitors to the county. Otherwise, they would have been previously reported.

The upshot is that probably all the birds you will likely see in a county will be found on this website's county checklist for that county. And if you see a bird that is not shown on that checklist, you probably have an unusual sighting on your hands! Get a photo if at all possible!

Caveat No. 3 is that the county checklists on this website do not give any indication of the frequency or abundance of the species listed. Some of the species shown may have been seen only once or a few times in the county. At the other extreme, some species are common, abundant and present throughout the year.

Further information

Here are some suggestions for getting more information about species or sightings in a particular location or county:

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