1494 U.S. NATIONAL MUSEUM BULLETIN 237 part 3 



seems not to be in earnest, as, notwithstanding the rapid movement 

 of their wings, their progress is slow. Now and then a bird pauses 

 in his flight to sing, supported for an instant on his widespread pinions. 

 Flight-songs also carry them up into the air. Occasionally a battle 

 ensues between two rival males, and sometimes they even roll and 

 tumble in the dust with locked bills and beating wings." In the sec- 

 tion on courtship is a description of behavior that probably has 

 territorial functions as well. The song sparrow's persistent songs, 

 six to eight per minute at dawn in spring (Forbush, 1929), are, of 

 course, associated with the maintenance of territory. 



The size of the individual territory in favorable habitat is less than 

 an acre. Robert E. Stewart and Chandler S. Robbins (1958) give 

 an interesting series of data on the population density of breeding 

 song sparrows in Maryland. (Population densities provide a basis 

 for estimating only maximum territory size, for it does not follow that 

 all the area censused actually fell within the boundaries claimed by 

 the males.) In 19.2 acres of " 'shrubby field with stream-bordered 

 trees' " were 21 territorial males; in 9.5 acres of " 'open hemlock- 

 spruce bog' (brush-meadow stage * * *)" were 3 males; and in 20.5 

 acres of " 'moderately sprayed apple orchard with infrequently 

 mowed ground cover * * *' " were 4.5 territorial males. 



Courtship.- — Witmer Stone (1937) writes as follows of his observa- 

 tions on Cape May: "In late March and April the air seems simply 

 filled with Song Sparrow song and at this time we see male birds 

 flying from bush to bush with neck stretched out, head and tail held 

 high, and wings vibrating rapidly. This seems to be a part of the 

 courtship display and as soon as the bird alights it bursts into song. 

 On March 21, 1925, and April 2, 1914, I have noted this performance 

 and the birds were evidently paired * * *." This behavior probably 

 was associated also with territory defense. To the account from 

 Forbush quoted in connection with territory may be added the same 

 author's statement that song sparrows "spend much time in the pleas- 

 ant pastime of courtship. The females seem to be modest and coy." 

 The duration of the periods of pair formation and between pair 

 formation and nesting seem not to have been recorded. A comparison 

 of the dates given for the height of the return of spring migrants and 

 for the beginning of general nesting in a given locality suggests that 

 a month or more often elapses in these "prenuptial" and "preliminary" 

 periods (Nice, 1943). 



The same males and females have been found mated to each other 

 in successive years (Hamill, 1926; Higgins, 1926). 



Nesting. — Building is carried on principally by the female, but 

 Ora W. Knight (1908) once saw a male apparently assisting his mate. 

 He was "more inclined to shirk his share, picking up material, dropping 



