Jody, The concept of avoiding double counting is implied in the nature of the CBC, and there is a spectrum in the level of attentiveness in avoiding double counting for different species, different locations, and by different birding parties. The key idea amidst all the variables, as you note, is maintaining the utility of the data for long-term interpretation of changes, and this involves consistency of monitoring (even if it is rough around the edges). Of course there is no realistic means for preventing double-counting of chickadees in a neighborhood with multiple feeders, but every year there is a concerted effort not to double count waterfowl at Stewart Park -- the highest tallies are typically taken instead of adding each observer’s sightings, or as I recall, one person is designated to count geese, gulls etc. on the lake.
Swans have only been documented on (I believe) 6 Ithaca CBCs in the past 100+ years, all in the last two decades. Whatever count total is used, this year is our record high count. I don’t recall any years like this one when we had multiple flocks in passage, so the previous count totals were likely highly accurate and not subject to being double-counted. However, the evidence suggests that a section-added count of ~400 is a 100% overestimate. Using the section-added total would likely be a gross deviation from the status quo with regard to the accuracy of past swan counts on our CBC. Like the coordinated effort at Stewart Park to prevent multiple waterfowl counts, the swan tally could be corrected with a bit of coordination in observations this year and foresight in future years (i.e., noting flock size, location, trajectory, and time). So, while I generally agree with the importance of maintaining the status quo in counting procedures, I don’t agree with projecting the status quo of a section-added count (i.e., for chickadees) on swans. Asher, section counts would not be denied their birds. As one can see from the map, section counts in fact help ascertain the accuracy of the migration tally. Bill E The evidence suggests some flocks were double and even triple counted, but as Ken pointed out there are still some things that don’t add up. Two pieces of information that would he -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
