Breeding Biology 



TERRITORIAL BEHAVIOR 



Arrival on the breeding grounds 



The Swainson's Warbler is one of the last of the southern 

 warblers to arrive on the breeding grounds, but it is earlier than 

 most of the northern transient members of the family. When I 

 visited the Dismal Swamp on April 11, 1969, all of the resident 

 breeding warblers except the Swainson's Warbler had returned. 

 Wayne's Black-throated Green Warbler had already begun to 

 nest. Since the foliage was only about one-third out, and since 

 Swainson*s Warbler occupies the shadiest part of the swamp, its 

 late appearance is probably timed with that of the foliage. 



Since males sing the first day on the breeding grounds, the 

 schedule of their arrival is better known than that of females; 

 but females have struck the TV tower at Tall Timbers Research 

 Station, Tallahassee, Fla., as early as the first week in April (Wil- 

 liam Dopson and James B. Cope, personal communication). At 

 the Dismal Swamp in southeastern Virginia, earliest males have 

 been recorded as arriving on April 15. On April 20, 1969, I ob- 

 served a mated pair on their breeding territory in this swamp. 



In the relatively late season of 1966, at my Macon, Ga., study 

 area, the local male population arrived during a period of about 1 

 week. The first four males arrived on April 12 ; by the next morn- 

 ing there were eight males ; there were nine on the 14th, and ten 

 on the 15th, the date I departed from the area. When I returned 

 on April 28 there were 19 males in the area. Apparently the males, 

 and probably the females, arrive at night. I was on the breeding 

 grounds 2 whole days preceding the arrival of the first males on 

 the 12th, and on that morning I was there before dawn. At day- 

 break on April 12, I heard the first Swainson's Warbler. 

 Homing 



Individuals that establish a territory one year may return to 

 the same place in succeeding years. John Weske banded a Swain- 

 son's Warbler on territory in the Pocomoke Swamp in Maryland 

 in May 1960, and the bird was recovered at virtually the same 

 place the following four seasons by mist-netters David Bridge and 

 Vernon Kleen. In my study area in the Dismal Swamp, a marked 

 male occupied the same general territory for 3 successive years. 



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