274 BULLETIN liG, UNITED STATES NATIONAL MUSEUM 



the feathers of the mantle are " fuscous " or " hair brown," broadly 

 edged with grayish white and subterminally bordered with brown- 

 ish black; the crown is grayish white, streaked with dusky; the 

 scapulars are " fuscous" to brownish black, broadly tipped, notched, 

 or spotted with pale grayish; the breast and flanks are less heavily 

 marked than in the adult. I have not seen this plumage described 

 elsewhere. At the next molt the adult winter plumage is assumed. 



Adults have a complete postnuptial molt in August; I have seen 

 one with primaries and secondaries molting as early as August 27. 

 In adult winter plumage the upper parts are uniform " fuscous," 

 with only slightly fighter ('"■ hair brown") edgings; the chin and 

 throat are white, spotted with " hair brown " ; there is a broad band 

 of " hair brown " across the chest and below it the under parts are 

 marked on the breast and flanks with hastate spots of " fuscous." 



A partial prenuptial molt of the body plumage takes place in 

 April and May, but some of the old winter feathers are generally 

 retained. In full nuptial plumage the head and neck are grayish 

 white, everywhere boldly streaked, or spotted, with black and slightly 

 suffused on the} crown with "'pinkish cinnamon"; the leathers of 

 the back are centrally black, broadl}^ edged with white and tinged 

 Avith " pinkish cinnamon " ; but the most striking features of this 

 plumage are the scapulars, boldly patterned with " pinkish cinna- 

 mon " and black, with narrow whitish tips; the white under parts 

 are boldly marked, especially on the breast and flanks, with hastate. 

 subcordate, or crescentic spots of brownish black. The cinnamon 

 colors fade during the breeding season to pale bufl' and eventually .o 

 svhite in July birds. 



Food. — On its breeding grounds in summer the surf bird feeds 

 almost entirely on insects, mainly flies and beetles. The analysis of 

 the stomach contents of eight birds, taken in Alaska and examined 

 by the Biological Survey, shows the following proportions : Diptera, 

 55.2 per cent; Coleoptera, 36 per cent; Lepidoptera, 3.8 per cent; 

 Hymenoptera, 3.3 per cent; Phalangidea, 1 per cent; snails, 5 per 

 cent; and seeds, 2 per cent. Mr. Dixon (1927) says of its feeding 

 liabits: 



Three days later s<-ven surf birds were found feeding in company at midday 

 uear tliis same spot. Tliis time they were foraging near the top of a very steep 

 talus slope that lay fair to the sun. t)nly a few scant flowers grew amid the 

 rocks, but insects were numerous and acti\e. One surf bird which, when later 

 collected, proved to be a male stood guard while the otliers fed. The slightest 

 movement on my part was sufficient to cause a warning note to be given by 

 this sentinel. When feeding, these birds ran hurriedly over the rocks, traveling 

 as fast or faster than a man could walk. When an insect was sighted the pur- 

 suing surf bird would stretch out its neck as far and as straight as possible. 

 Then moving stealthily forward the bird would make a final thrust and secure 

 the insect in its bill, much in the same manner that a turkey stalks a grass- 

 hopper. 



