Last time I wrote that in 2010, birders using eBird had reported seeing 298 species in York County. Since then, I’ve discovered a quirk in that data: In eBird, “species” is more than species. The tally is not as close to 300 as I thought!

Most birders have spotted birds that they couldn’t nail down to species, but many still make note of them. Rare is the field notebook without any “accipiter sp.” or “empidonax sp.” to account for those hawks or flycatchers that just didn’t reveal enough for a positive identification. Those entries and many similar ones are still acceptable, though, to eBird. For example, the York County list contains five scoter and three scaup “species.”

Hybrids are allowed on the list, too. Brewster’s Warbler, that handsome combination of Blue-winged and Golden-winged Warblers, gets its own line, as does the Mallard/American Black Duck mix.

Altogether, the latest count for 2010 shows 21 non-species, leaving just 278 true species on the list. Is 300 even attainable? It’s still worth a try. So far, eBirders have reported 116 species in 2011.

If you haven’t checked out ebird.org already, now is a good time to browse around. Registering lets you record the birds you see, keep track of your bird lists, explore dynamic maps and graphs, share your sightings, join the eBird community, and contribute to science and conservation. If you have previously registered for any BirdSource project, you can use your existing account on eBird.

But if you’re not quite ready to create an account, you can still use eBird to view graphs, charts, and maps showing the distribution and abundance of birds reported by thousands of other participants.

Wonder where to get started? Try this: visit ebird.org, follow the “About eBird” tab, and look near the bottom of the list of links in the right column for “Occurrence Maps.” Click to see how scientists have used the eBird data to create fascinating animated maps for many species. It’s amazing to watch the yearly ebb and flow of migratory populations on a base map of the United States, and a wonderful demonstration of the power of cooperative science.