GUADALUPE JUNCO 1097 



such as "sayal browu" aud "cliestuut." The two sets of eggs in the 

 National ^Museum were collected on Guadalupe Island, Baj a California 

 April 5 aud 12 respectively. The measurements of these sLx eggs 

 average 20.4 by 14.9 millimeters. 



Young. — Bryant (1887) noted birds a few days old on Mar. 10, 1886, 

 and he collected fully fledged juveniles on March 16. Kaeding (1905) 

 mentions fidly fledged young on Mar. 22, 1903. Brown and Marsden 

 {in Thayer and Bangs, 1908) found full grown juveniles on May 1, 

 1906, but they also found young still in a nest in May or early June of 

 1906. I found many full grown juveniles in streaked plumage in the 

 second week of June 1953. I estimate that 10 percent of the juncos 

 in the Nicoiiana thickets were juveniles but that in the cypress grove 

 the proportion was as high as 40 to 50 percent of the total. 



Plumages. — The Guadalupe junco appears to have the same 

 sequence of plumages as do other juncos. The early nestling stages 

 have not been described, but the juvenal plumage closely resembles 

 that of J. oreganus — streaked with dark brown on the entire head, 

 breast, back, and flanks, with the wings, tail, and abdomen essen- 

 tially like those of an adult. This juvenal plumage is presumably 

 lost in the late summer or fall in the first prebasic (postjuvenal) 

 molt, and the basic plumage thus acquu'ed has the same aspect as 

 that worn by adults. There is a prebasic (annual) molt by adults 

 following the nesting season, but no change in the aspect of the 

 plumage. Two out of three adult birds we collected in June 1953 

 were undergoing this molt, and many other molting adults were 

 seen at that time. Considering the early beginning of nesting in 

 the Guadalupe junco, it is likely that adult birds have completed 

 their molt by midsummer. As mentioned previously, there is no 

 evident difference in coloration between the sexes. 



Food. — The Guadalupe junco subsists on both insects and seeds. 

 Palmer {in Ridgway, 1876) mentioned that the bh'ds gathered ants 

 and their eggs as he turned over logs. In June 1953 we found most 

 insects rather scarce and ants particularly rare; no other observers 

 have mentioned the latter in the junco's diet. We noted that juncos 

 foraged in loose soil in the cypress grove and that they probed into 

 crevices in logs for moths and possibly other insects. The juncos 

 also fed on the calyces and ovaries of the Nicotiana flowers, which 

 were abundant in June 1953. No doubt many other kinds of plant 

 and insect food were utilized when the island was in its primordial 

 condition. Br3^ant (1887) states that "their food was principally 

 of seeds, a partiality being shown for the green seeds of the 'wild 

 lettuce.' " Whatever plant this may have been, it probably no 

 longer exists on the island. 



