1220 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 2 



do clash in mid-air, and fall to the ground in a flurry of beating wings 

 and scratching feet. For several days they chase each other for 

 hours along the boundary until it is apparently established. Then 

 both stop chasing and fighting and return to singing, unless one 

 wanders over the line. 



Should another male move in on another side, the established bird 

 has the same procedure to go through again. Sometimes when several 

 new males try to establish themselves in the vicinity the chasing 

 conflicts are almost continuous and revolve from one bird to another. 

 It may take the first bird many mornings to maintain his territory, 

 which may also have become much smaller than the many acres he 

 claimed on his first arrival, though still adequate for the needs of a 

 family. 



The sizes of the individual territories I found varied somewhat dur- 

 ing the 11-year study. Which they seemed to average about 3 acres, 

 some years most were less than 2 acres in extent, and in other years, 

 after a severe fire had swept the area, territories were of 5 or 6 acres. 



Stew^art and Robbins (1958) report breeding popvdation densities 

 in Maryland varying from a low of 7 territorial males per 100 acres 

 of "damp deciduous scrub with standing dead trees" to highs of 79 

 males per 100 acres of "abandoned field with open growth of young 

 scrub pine" and 80 per 100 acres of "unsprayed apple orchard with 

 unmowed ground cover." 



Observations on color-banded birds showed that usually the older 

 males were the first to return in spring, and each invariably came back 

 to the identical spots he had defended the previous year. Younger 

 males coming to breed for the first time had to find leftover spots or 

 try to squeeze into suitable places between already established 

 territories. Banded birds that did not return I felt certain had 

 perished, and the varying percentages of birds returning each year 

 suggested the death toll was higher some winters than others. Of 50 

 banded birds that returned in subsequent years, all but one of which 

 was banded as an adult, 27 returned the 2nd year, 12 the 3rd, 5 the 

 4th, 4 the 5th, and 2 the 6th year. 



One of these 6-year birds, as I have detailed elsewhere (1945), 

 reared two broods successfully with his mate that year. The other 

 6th-year male tried repeatedly to maintain his territory, but was 

 unable to do so against the much stronger new unhanded males. He 

 tried to chase them, but soon they were chasing him the most. After 

 the encounters he flew to the ground and rested, panting as though he 

 was very tired. He remained only a few days, then disappeared, and 

 I never saw him again. 



Often between territories were stretches of ground that neither 

 male defended and on which both fed, sometimes only a few feet apart. 



