i?filr L 
Pair M 
?- 
table expresses the a«i n number of minutes between oopulotlons 
in the different watohes. 
a, a. 
noon 
p # D, 
Kean for day 
2 April 
27 
38 
82 
37 
9 April 
31 
38-42 
60-64 
40-41 
23 April 
2.3-25 
41-44 
• 
33-55 
29-3 « 
Thus it seers that the frequency of copulation i« gre&tsr 
earlier tn the day than later and that thia effect la most ®ar v ed 
early in the season. The above table le baaed on all the airs 
under observe tion at the colony# Whan tha Individual pairs 
are considered separately one finds that some pairs show the 
influence of Use of day while others do not. The neat 
i bias ah w the rean interval between oo ulations for pairs 
L and V, the two which Inter euaoetded in rearing you nr, . 
a.m. 
noon 
p.m. 
Veaa for i 
i 
2 April 
17 
3* 
> , 4 
50 
9 A or 11 
20 
25-28 
40 
26 
33 April 
15-17 
• 
35-39 
17-21 
l8-2t 
2 Aoril 
51 
.43 
40 
44 
9 April 
40 
64-68 
31-39 
39-43 
23 April 
35 
54 
35-45 
37-41 
A prellmlahry hypothesis was that the frequency of 
oooulfttior r the interval between successive ones) was a 
Bon sure of sexual motivation. On could then teat whether 
it was sexual wotivatin which was responsible for &ttr* ing 
the birds to their ledges at certain tin.*- t« of d*y. One obvious 
difficulty is of course that my measure of sexual aotivation 
is really a Hi< ?*st Cosson Factor of the sexual motivation 
of the pair, nt in the same way ®ne nay try and expr 
attractiveness of the ledge for wa pair by tue percent of time 
they each eoend at it. For example if the male spends two 
hours and the female two and a half out of a watch of three 
hours the percentage for the pair is 
|co % ..".iim .*"'« ■ *- < 3 75$ 
tl % i 
If there were any correlation between attendance and sexual 
n-otlwtion we might expect to see it when the "percentage attend, 
otted against "interval between copula t is". The 
figure below shows the result of this ot# There appears 
to be a slight indication of a correlation but statistical teats 
show that although it goes In the right direction it right 
hove arisen by chance# 
