Reproduction 39 
there is no clear beginning nor ending to a song upon the ground 
unless one counts each rendering of the intermittent ditty, and 
all songs are not of this type. However a reasonably careful 
tabulation of all flight songs was made on every visit both at 
Evanston and at Ithaca. Now if we consider that the average 
length of a visit was the same in all months and if each month 
is properly weighted and averaged according to the number of 
visits, then at least relative figures may be obtained for the 
entire season. Thus of five January visits one flight song was 
observed, a percentage of .200 flight songs per visit. Similarly, 
in February, fourteen visits were made and six flight songs 
noted, a percentage of .428 flight songs per visit. Using this 
as a method of estimating amount of flight songs throughout the 
months of song we have the following tabulation: 
Average number of flight songs noted per visit from January 
to July 
January .200 per cent 
February 428 =“ 
March 160 
Apeik sso Soe ae ee Lon 
May 2.022 ‘° 
June igs. 2! 
July eee 
These figures are exceedingly conservative as far as total num- 
ber of songs may be concerned but they are pretty close to the 
truth as far as percentages are concerned. May is the optimum 
beyond question. May is probably the optimum in all respects 
as far as the entire breeding season is concerned (see below under 
enemies of young). June, as given here, may be a little too high 
for more time was spent per trip during this month than during 
other months. But even as given it shows the dropping off in 
flight song in this month, a dropping off which, in July, becomes 
very great indeed. Incidentally the total number of recorded 
flight songs was 287. 
There is, of course, a variation in songs dependent upon 
weather conditions. Fewer songs are sung when the weather is 
bitterly cold, especially if the day is also dark, though I have 
watched these birds, in February and March, climb into a stiff 
northwest gale, when the thermometer registered many degrees 
