It was established at Bay Bulls that five different individuls 
performed at some time during each period, although the maximum 
performances during seven periods varied from three to six birds. It 
was concluded that the sixth performer, on April 30, may have been a 
migrant. Peak performances at Salmonier for eight periods involved 
from four to five birds. In each locality, however, it was possible to 
keep track of individual performers. As a further example, on May 27 
at Bay Bulls, four individuals were performing sporadically from 9:30 
to 10:05 pem., and again from 10:20 to 10:5 p.m, but so quickly did 
some individual "go-up" and another "go-down!! that only two individuals 
could be recorded in the air at any given interval during these periods. 
(This was a particularly erratic bout of shift-work, but our field notes 
record other instances). Consequently, the winnowing charts (Figs. l 
and 2) show only the number of individuals performing at a given moment 
rather than the average or highest number during a given interval. 
Moreover, it is during the peak interval that each performer will 
winnow, if only for a short time. 
Table 2, Maximum numbers performing at any one interval during peak periods 
Date Location Wea ther Post-sunset Pre-dawn 
April 26 Bay Bulls 
April 30 of 
May oT n | 
May 5 tt Ovettcast 
May y 6 tt ue 
Clear moonlight 
tt 
wi it Oi 
May 9 Tompkin's tt 
May 10 a Clear no moon 
May 11 tt tt 
May 12 " TT 
May 13 tt tt 
May Ww " " 
powiwit | 
May 23 
May 26 
May 28 
May 30 
May 27 
Salmonier . 
"i 
4 
tt 
" 
Clear moonlight 
\5 
rmWwnowwb Wulnintn wl w or 
twnrowl 
