NUTTALL'S WHITE-CROWNED SPARROW 1299 



Such song gains in force and frequency until on the evenings when 

 copulation occurs he follows his mate about, singing loudly before 

 and after he mounts her. 



Copulation occurs most often during the half-hour before dark, but 

 may take place also during the day. The female follows her mate 

 about and trills persistently, fluttering her wings and raising her tail. 

 Suddenly she flies straight away from her mate, and lands either on the 

 ground or in a tree some yards distant. Her mate follows and lands 

 near her. He hops toward her, crown raised and tail lowered and 

 spread, flutters above her a few seconds, then flies to a nearby perch 

 and sings. I have seen the same pair copulate as many as 11 times 

 in one evening. The average for 21 pairs is 5 times. The period 

 during which the pair copulate lasts 3 to 6 days. 



Since immature birds begin their courtship at the same time as the 

 adults, they may pair as early as January, and the interval between 

 pairing and copulation may last 6 weeks or more. The long courtship 

 period characteristic of Nuttall's sparrow is a consequence of the fact 

 that courtship begins when both sexes are in the early phases of the 

 reproductive cycle, with immature gonads only a small fraction of their 

 breeding size. This is not true for the migratory races. 



In Nuttall's sparrow polygamy is not uncommon. In 5 years of 

 observation of color-banded birds at Berkeley, I found three cases of a 

 male with two mates. 



Nesting. — The typical nest site is similar in the four races. The 

 nest is usually placed either on the ground or a few feet above the 

 ground, under or within dense but not necessarily extensive vegetation 

 of whatever kind affords adequate concealment. Some of the species 

 of plants in which nests have been found are conifers, especially 

 young pines and spruce (Bolander, 1906; Farner, 1952; Jewett, 1916; 

 Johnston, 1943; Kobbe, 1900; McHugh, 1948; Ray, 1906; Warren, 

 1912); scrub oak, willow and alder (Farner, 1958; Grinnell, 1900; 

 Macoun, 1909; Ray, 1912); dwarf birch (Dice, 1920); bushes of wild 

 rose, lupine, sage, thimble berry (Jewett, 1916; Ray, 1906); composite 

 perennials such as Ericameria and Eriophyllum (Grinnell and Linsdale, 

 1936); many species of ornamental exotic shrubs; and, rarely, an 

 annual plant (Grinnell and Linsdale, 1936, found a Nuttall's sparrow 

 nest at Point Lobos in a 4-foot radish plant). Nests on the ground 

 may be placed in a tussock of grass, in densely matted perennials 

 such as Labrador tea, or, rarely, in a patch of moss (Grinnell, 1900). 

 They are often built at the base of scrub willows or conifers (Grinnell, 

 1900; Macoun, 1909; Ray, 1912). Occasionally the nests are placed 

 in exposed situations, as for example the Gambel's sparrow nest 

 Edward A. Preble (1908) found in a tuft of short grass beside a 

 much-frequented path in a field. Some atypical sites include one 



