ML646227730

観察結果の詳細

Counted individually. Sightings during exercise walks previously this fall suggested to me the number of swifts amassing before sundown was above average this year, but it would be insane to estimate a number from watching them swirling across the sky. This was the first time this season I have stayed to count them as they enter the weepholes. They came in very high at 4:12PM and didn't wait long to start going to roost. During most of my prior such censuses, I've seen swifts go in and then go out, or feint going in. Not this time. None were exiting, which made counting easier. The peak frequency was at 4:30PM, with a rapid drop-off as the 4:44 PM sundown approached. Prior winter's censuses have been in the 100-350 range. I hypothesize the higher counts this year may be due to higher November temperatures until this past week, and the absence of any Merlins or Peregrines stalking, catching, and eating swifts every day from the nearby wires.