288 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



ness. He noticed that more stones were used where the nests were 

 built on earthen floors, than when built on rocks, and says that the 

 birds line the passageway and the nest cavity before the nest is built. 



Philo W. Smith, Jr. ( 1904) , found 13 nests in an extensive limestone 

 quarry in Texas and says that "where the nests were located at the 

 bottom of the quarry there was no attempt at building a walk, but 

 when the nest was situated in a crevice the walk was invariably there 

 provided." 



Eggs. — Five and six eggs are the commonest numbers laid by the 

 rock wren, but sometimes as few as four constitute a full set, seven or 

 eight are not rare, and as many as ten have been found in a nest. 

 Ovate is the commonest shape. The ground color is pure, glossy white, 

 and the eggs are sparingly and irregularly sprinkled with fine dots 

 of reddish brown, "cinnamon-rufous," or "burnt umber." The meas- 

 urements of 50 eggs in the United States National Museum average 

 18.6 by 14.8 millimeters; the eggs showing the four extremes measure 

 20.3 by 15.2, 19.6 by 15.7, 15.8, by 14.7, and 18.8 by 13.7 millimeters. 



Young. — Generally two and perhaps sometimes three broods are 

 raised in a season. As the male has been seen to assist his mate in 

 building the nest, and to feed the female on the nest, it is fair to 

 assume that both parents help in the feeding and care of the young. 



Plumages. — I have seen no very young rock wrens, but those in 

 Juvenal plumage differ from adults in having the upperparts faintly 

 and narrowly barred with dusky, instead of streaked, and lacking 

 the white spots ; the light brown, "vinaceous-cinnamon" rump is im- 

 maculate; and the underparts are whiter than in the adult and un- 

 spotted, with a brownish wash on the flanks and under tail coverts. 



Dickey and van Rossem (1938) say of the molting of this wren in 

 El Salvador : "Juveniles taken on the Colinas de Jucuaran as late as 

 September 7 have only just commenced the postjuvenal body molt. 

 Adults from the same locality show the annual molt to commence 

 about August 1, and a specimen taken September 7 is in practically 

 complete, fresh, fall plumage. There is no spring molt discernible 

 in numerous specimens taken between February 26 and March 26, 

 and it seems likely that none normally occurs." 



I have seen adults molting as early as the first week in July and 

 at other dates during that month ; other adults that I have examined 

 have been in worn breeding plumage as late as August 7, and others 

 had completed the postnuptial molt during the first two weeks in 

 September. 



Food. — Very little seems to have been published on the food of the 

 rock wren, no detailed analysis having been made. Living as it does 

 in rocky barrens, its food is of little importance to the agriculturalist. 

 Its food probably is much like that of other wrens, consisting mainly 



