[cobirds] Cohorts

            The ABA blog on redpolls that Ted Floyd cited the other day goes into amazing depths for a casual bird watcher who might sink in the esoteric literature on redpolls, DNA, statistics, etc.

            One minor point, though, that Bill Schmoker mentioned, raises a question I have pondered lately. He said, ". . . Flocks coming to feeders are probably under-counted. For example, if someone counts and reports 75 redpolls at a feeding station, there well may be a pool of 200 or 300 birds coming and going."

            I remember someone saying that if you see 4 Black-capped Chickadees at a feeder at one time, you probably have 16-20 actually patronizing your largess.       

            At our feeders we commonly see 5-10 House Finches at a time. However, when we walk in the field below the house, in a big thicket of wild plums 200-300 yards away, we typically flush 60-120 House Finches.

            Do many species, during non-breeding seasons, move around in small cohorts compared to their local numbers? Do all those House Finches in the field sample our feeders sometime during the day? Or do some scorn our offerings for natural food or a neighbor's feeders?

Hugh Kingery
Franktown, CO

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