Every week you count the birds (at your convenience) for a two-day stretch, note the weather, and report the results online. You pay $15 for a data-entry kit and all the bird-counting that your heart desires. Urban, suburban, rural — all locations are valuable.
Here is M.'s and my first count of the year. The second and third columns are "average group size when seen" and "average group size per count period," which since it is the first count are the same as the head (or beak) count.