The count only began this morning, and already 2,282 reports have come in, detailing 338 species and 153,792 total birds already seen.

The Great Backyard Bird Count is an annual, four-day event that has birders of every stripe and feather outside, checking to see what kinds of birds and how many are in the vicinity.

The idea is that you go outside for a minimum of 15 minutes, log what you see and report back to a central database. It continues through Monday.

Even people who can’t get outside can watch the counts progress online at www.birdsource.org/gbbc

The reason this is important is that bird populations are in constant flux.

This year, for instance, I think I’m seeing more house finches than usual around my feeders. There’s not necessarily an earth-shattering reason, but overall, population trends can tell scientists much about what’s going on in the natural world.

Maybe cold temperatures are affecting bird populations in a particular region. Do the data indicate some species are migrating sooner? Are diseases like West Nile virus affecting bird populations? Are there areas that are really important for birds that remain unprotected?

Getting data from thousands of birders across the nation is a good way to start to untangle the mysteries.

The count is led by the Cornell Lab of Ornithology and National Audubon Society, with Canadian partner Bird Studies Canada and sponsorship from Wild Birds Unlimited.

If this one whets your counting whistle, you can participate in other citizen science programs, too, such as the Christmas Bird Count or Project FeederWatch.

Want to branch out to more kinds of wildlife?

Check out the Journey North program, which I wrote about a blog post yesterday. On it, citizen scientists mark the progress of spring as it progresses north (or, in the fall, south).

The Association of Zoos and Aquariums sponsors a FrogWatch USA program for citizen scientists to report data about the calls of local frogs and toads.

And if you REALLY want to get involved, check out SciStarter, which is considered to be the largest aggregator of citizen science and crowdsourced projects.

You can get started by picking one of more than a dozen topics — astronomy, say, or birds or weather. Or you can pick an activity — at home, at the beach, on a hike.

There are dozens upon dozens of cool opportunities.

The site was begun by Darlene Cavalier, an area resident and former 76ers cheerleader who also started www.ScienceCheerleader.com, described as “a blog that works through NFL and NBA cheerleaders-turned-scientists and engineers to promote science literacy and the involvement of citizens in science and science-related policy.”

Yay, Darlene!