NUTTALL'S WHITE-CROWNED SPARROW 1309 



when there is no obvious cause i'or alarm or excitement. Lone migrants 

 frequently utter this note over and over again when they arrive on the 

 wintering grounds in early fall. Flock members utter it as they go to 

 roost when the note may be repeated with ever-increasing frequency, 

 followed by a burst of song. A squabbling note that defies syllabifica- 

 tion may be used by two birds as they dispute a morsel of food, or by 

 a lone bird as it forages. One other call note is more restricted in its 

 use: a warning "tit" given by parents with nestlings or young 

 fledglings makes the young stop their food cries and stay quiet. As 

 this note is not used until after the young hatch, one can be sure that 

 a pair using it has young rather than eggs. 



The habit of this species of singing at night is so characteristic that 

 it is one of the best ways to identify the bird to the layman. Song 

 in NuttalTs sparrow may express by itself or accompany other ex- 

 pressions of at least six unmistakable purposes or attitudes of mind: 

 defiance or warning to territorial rivals, the search for a mate, sexual 

 excitement, announcement of territorial boundaries (as when used on 

 patrol during the incubation period), interest in the female's return to 

 her eggs, and fright or physical shock. Examples of the first five 

 have been given. I have two examples of the sixth (fright or shock). 

 In the first, a male foraging with its mate dove into a clump of juniper; 

 when I suddenly shook the bush into which he had disappeared, he 

 burst into song. The second is furnished by Thomas L. Rodgers 

 (pers. comm.). While transporting Nuttall sparrows in darkened 

 cages by car through several miles of city traffic, he noticed that each 

 time he put on the brakes suddenly, the sparrows would just as 

 suddenly burst into song. 



The song of the white-crowned sparrow is best described as a theme 

 common to the species, with an almost infinite number of variations — 

 racial, populational, and individual. The musical elements common 

 to the song of the Pacific Coast races consist of one or two initial 

 notes held for nearly half a second each, followed by two or more 

 rapidly sung notes or by a trill or both. On this simple theme are 

 built a wide variety of melodies, from robust simple tunes like those of 

 Berkeley Nuttall's sparrows to the more delicate and complex melodies 

 of Friday Harbor Puget Sound sparrows. So similar is the quality of 

 voice in all members of the species that a white-crowned sparrow song, 

 once learned, is unmistakable, no matter what the dialect. The racial 

 and populational variations are like different melodies sung by the 

 same voice. The individual variations are like the same melody sung 

 with different accents. 



NuttalTs sparrows and mountain white-crowned sparrows use 

 rhythmic patterns closely related to each other. GambePs sparrow 

 uses a markedly different pattern described here in detail, and the 



