LE CONTE'S SPARROW 769 



They are ovate and only slightly glossy. The ground is grayish 

 white, speckled, spotted, blotched, and clouded with "snuff brown," 

 "Saccardo's umber," "cinnamon brown," or "Mars brown," with 

 undermarkings of "light Quaker drab." These markings are gen- 

 erally more or less ev^enly dispersed over the entire surface. The 

 measurements of 50 eggs average 18.0 by 13.7 millimeters; those 

 showing the four extremes measm-e 20.4 by 13.9, 19.7 by 15.0, 16.3 

 by 13.0, and 18.3 by 12.7 millimeters. 



Young. — The length of the incubation period is not loiown accu- 

 rately. The nest I found in northern Michigan contained five eggs on 

 June 4, 1935, three of which hatched on June 16 and 17, a period of 

 12 to 13 days. Incubation should not require any more time than 

 this, judging by the requirements of related species of similar size, 

 and might even take less under ideal conditions. 



Incubation is performed entirely by the female while the male 

 guards the territory and sings nearby. On June 17, 1935, when the 

 female was brooding and feeding three newly hatched young and 

 incubating one unhatched egg, I watched the nest closely for 225 

 minutes (11:15 a.m. to 3:00 p.m.). In this time she brooded for 146 

 minutes (65 percent) and was away for 79 minutes (35 percent). She 

 left the nest 16 times; her periods of brooding averaged 9 minutes 

 with extremes from 1 to 21 minutes; her absences averaged 5 minutes 

 with extremes of )j to 20 minutes. At no time was I sure that the 

 male fed the young, but they were fed 10 times during this period at 

 an average interval of 21.4 minutes, with extremes of 5 to 41 minutes 

 between feedmgs. 



At hatching these three young weighed 1.7, 1.7, and 1.8 grams re- 

 spectively. One young at one day of age weighed 2.5 grams, one at 

 two days weighed 3.4 grams, and one at three days 4.5 grams. The 

 skin color of newly hatched Le Conte's sparrows is lighter and pinker 

 than that of Savannah sparrovv^ young. The sparse natal down is 

 wood brown. 



Plumages. — T. S. Roberts (1932) thus describes the juvenal plum- 

 age: "A general suffusion of pale tawny or buffy-yellow above, below, 

 and on sides of head; very little chestnut above; the color on hind- 

 neck and median crown-stripe tawny yellow; streaked more or less 

 thickly across breast with narrow blackish lines, bend of wing white 

 in four specimens, very pale yellow in two ; tail obscurely barred. By 

 September the throat and abdomen are becoming paler (whitish in 

 some spechnens), the bird generally less tawny, with chestnut ap- 

 pearing on head and back, and the breast-stripes more sparse; the 

 latter disappear with the completion of the postjuvenal molt." 



R. W. Dickerman (1962) adds the following details, which help 

 distinguish the juvenal Le Conte's from the juvenal Nelson's sharp- 



