68 



NORTH AMERICAN FAUNA 69 



In the Dismal Swamp on June 3, 1966, a Swainson's Warbler 

 shifted from perch to perch during the first half hour or more 

 of the morning song. The bird started singing at 4 :27 a.m. It sang 

 from the first location for 11 minutes, from the second for 10 

 minutes, from the third for 10 minutes, from the fourth for 4 

 minutes, from the fifth for 1 minute, and from the sixth for 

 1 minute. It began feeding and singing from the ground at 

 5:15 a.m. 



Seasonal song cycle 



The song period in the breeding range lasts from 5 to 6 months, 

 depending on locality, but the most vigorous singing occurs during 

 April and May. Males still mated in June and July sing almost as 

 frequently as earlier in the breeding season. Singing is fairly 

 regular but mostly in the morning until about August; it is 

 sporadic from mid- August to mid-September when birds begin to 

 leave the breeding grounds. 



In floodplain forests of the Ocmulgee River in Georgia and the 

 Arkansas River in Arkansas, I heard individuals singing daily 

 in July and August. On August 6, 1966, during a 2-hour period 

 (11 a.m. to 1 p.m.) when I was in a canebrake near Pendleton 

 Ferry, Ark., a male sang 93 songs. In this same area on Septem- 

 ber 7, 1968, four males sang sporadically in the morning until 

 about noon. They sang complete, incomplete, and whisper songs. 

 Much of their singing was instigated by Carolina Wrens, which 

 are among the loudest songsters of the southern woods. 



The male sings vigorously following arrival on the breeding 

 ground and until the pair bond is formed. Then, while traveling 

 with and courting his mate during the prenesting period, he sings 

 very little. Most of the singing is during the first 2 or 3 hours 

 after daylight. After 7:30 or 8 a.m. during this period males may 

 sing only half a dozen songs during the rest of the day. Such 

 songs later in the day are usually for the purpose of rallying the 

 mate. 



During nest building, singing may be sporadic, and often very 

 little singing is done. The male may sing infrequently in the morn- 

 ing while the female is working on the nest, but in the afternoon 

 when nest building is at a virtual standstill the pair remains 

 together and the male sings hardly at all. On the first day of nest 

 building, a Dismal Swamp male sang only one cadence, of 7 

 seconds, between 9 a.m. and 6 p.m. The next day he did not sing 

 at all after 9 a.m. 



During incubation the male sings more often than during the 

 courtship, mating, and nest-building periods. One of the functions 



