fime of Year 
The earliest date on which nesting populations can be determined 
from a study of winnowing birds was not ascertained, as no observa-~ 
tions were made on Manitoulin Island during the latter half of May, 
Indications are that winnowing counts made during April and the first 
half of May include transient individuals and so cannot be relied upon 
as indicators of nesting populations, Certainly by June 1, and most 
likely by a week or ten days prior to that time at the latitude of 
Manitoulin Island (46° n. lat.) the transient individuals have passed 
bye Winnowing was in full swing during the first week in June, but by 
the 15th of that month there were indications that it was starting to 
subside. Up to the time of my departure on the 23rd, however, it had 
not subsided much more than one-third from the peak of activity in 
early June. 
Winnowing does not necessarily cease when the young birds reach 
flying age, since one male was still performing regularly ten days 
after its young were flying. A. C. Bent in his "Life Histories of 
North American Shore Birds" (Bull. 142, U.S. National Musewm, 1927) 
gives the peak dates for eggs as May 12 to June 2 in Utah, May 28 to 
June 10 in Alberta, and June 3 to June 1) in the Magdalen Islands, 
Quebec, Allowing for an incubation period of 20 days, a downy young 
caught on June 3 on Manitoulin Island was one to two weeks earlier than 
would have been expected, This early nesting may have been due to the 
abnormally early spring in that area this year -- or possibly nesting 
begins earlier in that area than would be expected from the dates 
cited by Bent, : 
Distance between Stops 
Winnowing snipe under ideal conditions were audible for a distance 
of one-half mile by actual test. This means that to eliminate likeli- 
hood of duplication listening stops should be spaced one mile apart. If 
one minute were spent in listening and two minutes in driving, ten stops 
could be covered in a 30-minute period. In most areas accessible to 
highways, however, there is insufficient mipe habitat for setting up 
a ten=-mile route. Therefore, it may be expedient to adopt a shorter 
route, a longer listening period, or both. If stops are spaced one- 
half mile apart, care must be taken to avoid duplication. 
Length of Stops and Number of Stops 
A statistical analysis was made of the data obtained at one station 
during the height of the winnowing period on the mornings of Jue ) and 
5 and the evening of June kh, The coefficient of variation was computed 
for stops of one, two, three, four, and five minutes duration in both 
morning and evening, during the periods from 70 to 40 minutes before 
sunrise and 5 to 6 minutes after sunset, respectively. The number 
of stops required to limit results to a sampling error of 10 percent 
48 
