David et al., > All the birds are flying the same direction while other critters have random > flight paths.
Is this really a safe assumption? Last night I did some moon watching and the majority (just barely) of birds were headed westish. But others were flying south, some northeast, etc. I was fairly confident these were birds and not bats, but Mike made a good point about optics (I was using 10x binocs) and wasn't videoing so I have no way to prove to myself (or you guys) what I was seeing. In any case, I checked out the radar and there was decent volume, but the radial velocity had a trend of movement to the SW, but with a lot of scatter. Again, were these birds? I think so. Perhaps variation in the direction of movements is more apparent where I am along the gulf coast where topography and bird ecology (water-crossing avoidance vs not; trans-gulf vs circum-gulf; etc) significantly alter the behavior of individual birds. I can imagine that farther north birds are pretty much bombing south (although no doubt topography and ecology are important there, too). I have had similar experience listening to call notes - where you can pick out birds going in all directions. So I think this phenomenon is real, at least here. Happy listening, Erik Johnson S Lafayette, LA (~40mi N of the Gulf of Mexico) [email protected] > On Fri, Sep 4, 2009 at 5:30 AM, David > Mozurkewich<[email protected]> wrote: >> On Fri, 2009-09-04 at 02:53 -0600, Ted Floyd wrote: >> >>> I should think that, given distant and fleeting views of such animals, >>> there's the potential to over-count birds by accidentally counting bats >>> and moths. Any pearls of wisdom on this one? >> >> Ted, >> >> All the birds are flying the same direction while other critters have >> random flight paths. This eliminates most false alarms and is good >> enough except when the birds are a minority of your detections. >> -- >> David Mozurkewich >> Seabrook, MD USA >> >> >> -- >> NFC-L List Info: >> http://www.NortheastBirding.com/NFC_WELCOME >> http://www.NortheastBirding.com/NFC_RULES >> >> http://www.mail-archive.com/[email protected]/maillist.html >> -- >> > -- NFC-L List Info: http://www.NortheastBirding.com/NFC_WELCOME http://www.NortheastBirding.com/NFC_RULES http://www.mail-archive.com/[email protected]/maillist.html --
