It's President's Day, and if you plan to spend any time outdoors, do a good deed for the birds.

Today is the final day of the 10th Annual Great Backyard Bird Count, a project that asks backyard birdwatchers (along with the rest of us) to note the number of birds in their backyard, local park, or any other outdoor area.

Doing so helps researchers track bird populations, and gauge how they are faring in various habitats.

It's easy. It requires absolutely no expertise. And you get to build up some good karma for practically no effort at all. Just count the number of birds you see at any one time during a within a 15 minute period. Then submit that tally online at birdcount.org.

Your data is gathered by the National Audubon Society and the Cornell Lab of Ornithology, where researchers use it to create a long-term record of the diversity and distribution of bird species.

This also provides information -- or a sort of snapshot -- about how environmental changes. These include changing weather patterns and growing cities and suburbs affect bird species and flock numbers.

The researchers rely on volunteers because bird flocks are constantly in flux, and are basically impossible to track by a single group.

The counts inform researchers in several ways. For instance, they learn about the impact of winter snow and cold temperatures on bird populations, the timing of bird migrations, the spread of bird diseases, such as West Nile virus, changes in bird diversity in cities, suburbs, and rural areas, and if a species population has declined to the point of requiring conservation efforts.

If you want to help, here are a few ways to tally up the birds:

• Count the highest number of birds of each species that you see together at any one time. For instance, you might see several finches within 15 minutes period, in numbers of six, three, and then one -- jot down six, or the greatest number.

• If you want to count a large flock, record the birds within a small area. Then, multiply that number by your estimate of the actual flock size. Say you count 20 birds in an area that you think is about one-fifth the size of the entire flock. Your estimate will be 100 birds within the flock.
  

• If you're trying to determine or distinguish various species, try the resources at birdsource.org.