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Night Migration of Birds 
By JOHN BAYLESS 
MOON-WATCHING for migrating birds can be exhilarating when the birds 
are moving or dull when they are not. In either case, one provides a series 
of Chicago Park District patrolmen with a “now I’ve seen everything” 
report if one chooses, as we did, an observation post in a Chicago park. 
The complete disbelief, followed by wonderment, then curiosity (were we 
really seeing any birds?), and finally the baffled “I suppose they’re harm- 
less” departure made the effort worth while even on an unrewarding 
night. 
Our experiences in moon observations so far bear out the generally 
accepted belief that birds do take advantage of prevailing winds and avoid 
head winds while on migration. Our big count in October was made with 
north and northwest winds 4 to 9 m.p.h. at ground level and NNE at 10 
to 15 m.p.h. at the 2,000 foot level. A cold front had arrived just 24 hours 
earlier than our start that night. In five hours of observation, we saw 115 
birds apparently riding the north wind toward the warmer south. The 
next night, with the temperature some 10 degrees higher at 50° but with 
a 15 m.p.h. wind from the southwest, shifting to south during our one 
hour and ten minutes of observation, we saw no birds. The weather 
bureau reported a 40 m.p.h. wind from the SSW at the 2,000 foot level 
that night. 
We were participating in a moon-watching bird count conducted at 
many points in the country by bird watchers at the request of Robert J. 
Newman, Assistant Curator, Museum of Zoology, Louisiana State Uni- 
versity, Baton Rouge 3, La. Mr. Newman and others at the university 
have worked out a mathematical formula and system through which ob- 
servations by watchers are converted into valuable calculations of the 
number and type of birds migrating in a particular area at the time of 
observation. 
The observations are made when the moon is full or nearly so. The 
observer must have a glass which will take in the entire face of the moon, 
preferably a 19 power or more telescope; a comfortable chair in which he 
can lean back; fairly good vision; the ability to tell time; and most of 
all, patience. . 
Our first attempt at moon-watching for birds was an absolute failure, 
as a few minutes of squinting at the moon through a 20-power, coated 
lens spotting scope just about blinded us. Then we wrote to Mr. Newman 
and got his full set of directions. The moon did not blind us when we 
used a cardboard shield with a hole through it for the eyepiece. The shield 
permitted keeping both eyes open. We found we could watch as long as 
an. hour and a half at a stretch before changing observers. A century-old 
steamer chair (brought home by Anne’s great-grandfather after an ocean 
voyage) provided just the right position for relaxing under the telescope 
on its tripod. A lawn chair probably would serve equally well. A word of 
