SAN LUCAS ROBIN 1 69 



20.5 millimeters; the eggs showing the four extremes measure 33.0 

 by 20.8, 28.3 by 22.1, and 28.5 by 19.1 millimeters. 



Plumages. — Strangely enough, neither Mr. Frazar nor Mr. Brown 

 ever collected any young birds, though they took close to 200 adults. 

 It is a pity that collectors neglect to take immature or molting birds, 

 which are always scarce in collections and are exceedingly interesting 

 to students of plumages and often indicate relationships. Fortunately, 

 I have in my collection a young male San Lucas robin in juvenal 

 plumage, taken by Chester C. Lamb in the Laguna Valley, at 6,000 

 feet, on July 29, 1929, 69 years after the discovery of the species. It 

 is about half grown, but fully feathered on the body, with a very 

 short tail. The upperparts are similar to those of the eastern robin, 

 but paler; the pileum is "olive-brown," and the back is only slightly 

 paler; the light spots on the back are larger and a paler buff than in the 

 eastern bird ; there is much more white on the underparts, where the 

 extensive rufous of our familiar robin is replaced by a very limited 

 suffusion of "pinkish buff" on the chest, sides, and flanks; the dusky 

 spotting on the underparts is about the same as in our bird, but the 

 white tips of the outer tail feathers are very narrow. 



In all the large series I have examined I could not find one molting 

 bird. Most of the specimens are in the pale, faded nuptial plumage, 

 in which the underparts are pale "cream-buff" or paler, mixed with a 

 large amount of dull white, sometimes nearly all white; I find birds 

 in this plumage through August and up to September 2, mostly in 

 worn condition. 



There are no birds in the series that were taken late in September 

 or in October. But from November 10 and through December we 

 find birds in fresh autumnal plumage, in which the underparts are 

 clear, rich "ochraceous-buff" or "chamois"; these are probably fall 

 adults. The inference is that the postnuptial molt of adults, and 

 probably the postjuvenal molt of young birds, are accomplished in 

 September and October. 



In the series are many fall birds and some spring birds that show 

 more or less ashy clouding or obscure spotting on the chest, in some 

 cases forming an almost solid pectoral band. Mr. Brewster (1902) 

 was probably correct in suggesting, in his extensive remarks on their 

 plumages, that this and the dark bill, which is not always correlated 

 with the ashy clouding, are signs of immaturity. If this idea is the 

 correct one, it means that young birds can usually be recognized by 

 these characters all through their first year and do not assume the 

 fully adult plumage until their second fall. 



Voice. — Mr. Brewster (1902) quotes from Mr. Frazar's notes: 

 "The song resembles that of the eastern robin, but is weaker and 



