NATURAL HISTORY OF THE SWAINSON'S WARBLER 55 



yet returned. When I returned on April 20, I found birds paired 

 in at least one territory, and by April 23, nest-building had started 

 in that territory. 



The earliest nesting anywhere is reported by Wayne (1910, p. 

 150) who collected eggs containing small embryos on April 28, at 

 Charleston, S.C. However, May 1 is about the average date for 

 the beginning of nesting throughout the Swainson's Warbler 

 range. 



Nest building at Macon, Ga., and Pendleton Ferry, Ark., started 

 about 3 weeks after the first males arrived on the breeding 

 grounds. A completed nest ready for eggs was found at Macon 

 on April 27, 1946, and nests with full clutches were found by May 

 3, 1945, A nest containing one Swainson's Warbler egg and three 

 Brown-headed Cowbird (Molothrus ater) eggs was found at 

 Pendleton Ferry on May 1, 1967. This nest was probably con- 

 structed during the third week in April. 



In the Dismal Swamp the earliest record of nest building is 

 April 23, 1969. This is about 8 days after the average arrival date 

 of first males. In this same area I observed two nests under con- 

 struction on May 1. 



On the Allegheny Plateau near Charleston, W. Va., Sims and 

 DeGarmo (1948, p. 4) state, nest building begins about 2 weeks 

 after arrival on the breeding grounds. They found a completed 

 nest as early as May 1. 



Renestings or second nestings occur throughout June and into 

 early July. Perhaps the latest date is a nest with slightly incubated 

 eggs found on July 13, 1886, at Savannah, Ga. (Perry 1886, p. 

 188) . Young from this nest would have fledged about August 1. 



Nest site and materials 



For three or four days before nest building, and possibly longer, 

 another activity of the pair is the examining of nest sites. The 

 male of a pair that I watched at this activity led the way more 

 than his mate, and at times he examined nest sites alone. One 

 might therefore conclude that the male selects the nest site. 



The average height of 10 nests in various localities was 4 feet 

 0 inches, with a range of 1 foot 9 inches to 6 feet 3 inches. Nests 

 are usually built in the predominant understory vegetation (fig. 

 23). In the Dismal Swamp, nests are frequently placed in green- 

 brier vines (fig. 24), as well as in Japanese honeysuckle, sweet 

 pepperbush, and switch cane (Arundinaria tecta). 



Most nests in my Dismal Swamp study area were located within 

 30 feet of a road or path. Vegetation in these situations is denser 

 because of better exposure to light. 



