In order to gain a better understanding of the condition of the Delaware Bay stopover from year to year, we have conducted aerial and ground surveys of shorebirds across the entire Bay since 1986. These counts are conducted annually, in mid-late May at the height of the shorebird stopover in Delaware Bay. Using a combination of aerial surveying, observation from boat along the shoreline, and on-the-ground observers, we can develop a more robust estimate of the shorebird population on the Bay.
On a given day of the season's count, observers are stationed across Delaware Bay beaches to conduct ground counts simultaneously with the team in the airplane. We don’t consider our counts to be estimates of the total population because we don’t know what proportion stopover in the bay (although we are closing in on that number with our resightings project). Moreover, even when peak numbers are present, some may not have arrived, while others may have already departed. The counts do, however, provide a key indicator of the condition of the Delaware Bay stopover as do the other species counts.
Our aerial counts are carefully designed so that they not only tell us the peak numbers of each species as accurately as possible but also a measure of the degree to which numbers vary across the stopover season. These are not just sample counts from which the total is estimated by extrapolation. These are counts of all shorebirds using the Delaware Bay.