Scott Baron mentions seeing 46 birds in a half hour while watching birds
migrating in front of the full moon.
Scott Weidensaul, in his excellent book "Living on the Wind: Across the
Hemisphere with Migratory Birds" (p. 30) tells how to calculate from this
observation, the number of birds per hour based on the percent of sky our half
degree moon occupies.
Turns out that during the hour last night when, Scott B. was watching, the
estimated birds per hour passing that location was nearly 32,000 (347.45 x 46 x
2). This is based on the moon occupying 1/695 of a circle (not counting the
lowest couple of percent of the horizon, or 1/347.45 of the visible sky.
Jerry Blondell
retired EPA statistician.
Date: Wed, 30 Sep 2009 20:58:00 -0700 (PDT)
From: Scott Baron <brnpelican@xxxxxxxxx>
Subject: [Va-bird] nocturnal migration
When I got out of my car after arriving home at 11pm, I almost immediately
heard birds overhead. I noted the almost full moon so I went inside to get my
spotting scope. Despite having been a birder since childhood, it was the first
time I've viewed the moon to look for migrants. I counted approx. 46 birds (I
lost count, etc.) in about a half hour of viewing the moon which is currently
in the southern sky. I heard approx. the same number of bird calls.
What a neat experience. And the moon itself is wonderful as well.
Scott Baron
Fairfax, VA
