70 



NORTH AMERICAN FAUNA 69 



morning the pause between courses is so brief that they seem to 

 run for half an hour or more. Norris and Hopkins (1947, p. 8) 

 noted that the average interval between songs of a male at Tifton, 

 Ga., was 10.7 seconds. 



The rate of singing is usually faster at the beginning of a course 

 of songs (see table 3). During the first hour of morning song on 

 June 2, a Dismal Swamp male sang at a fast but gradually di- 

 minishing rate of speed: nine songs per minute for the first 8 

 minutes, and five or six per minute thereafter. 



The rate of singing is sometimes relatively constant over long 

 periods of time. A male in the Ocmulgee floodplain forest on April 

 19 sang between 40 and 46 songs (40, 42, 46, 43, 42) in each 

 15-minute period from 8 to 9:15 a.m. Table 4 shows songs per 

 15-minute interval by a male in the Dismal Swamp. 



Table 3. — Songs per minute in courses by a territorial male Swainson's 



Warbler 



[4:15 p.m. to 6:43 p.m., 15 June 1966, in the Dismal Swamp in Virginia. Data from 



Meanley, Wilson Bulletin, 1968, p. 75] 

 Minutes in course Time Songs in each minute 



5 . 4:15-4:20 8, 5, 5, 3, 2. 



5 4:27-4:32 8, 6, 5, 2, 4. 



6 4:40-4:46 7, 7, 7, 4, 4, 4. 



13 4:50-5:03 8, 6, 4, 5, 5, 4, 5, 6, 6, 5, 5, 4, 1. 



12 5:13-5:25 9, 6, 5, 4, 5, 4, 4, 4, 3, 4, 4, 2. 



5 5:26-5:31 5, 5, 5, 6, 5. 



3 5:48-5:51 8, 4, 1. 



2 6:14-6:16 5, 5. 



5 6:33-6:38 7, 5, 3, 4, 2. 



3 6:40-6:43 5, 6, 4. 



