714 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 2 



The measurements of 40 eggs average 19.0 by 14.7 millimeters; 

 the eggs showing the four extremes measure 21.4 by 14.0, 19.5 by 

 16.9, 16.9 by 13.8, and 17.2 by 13.^ milluneters. 



Plumages. — The juvenal plumage "is similar to savanna * * * 

 but black streaking of crown and back much narrower, buffy yellow 

 coloration paler * * * finely streaked on chest, sides, and flanks" 

 (R. R. Graber, unpublished Ph. D. thesis, Univ. Oklahoma). 



First winter and subsequent plumages are "very different from the 

 adjacent breeding or migrant races in being very much darker and 

 browner, with a great development of black streaking above, and more 

 heavily streaked with black (not brownish or blackish brown) below" 

 (J. L. Peters and L. Griscom, 1938). 



There is no prenuptial molt or feather growth. 



Foraging behavior. — This Savannah sparrow forages on the marsh 

 mud and in tangles of salt grass, sahcornia, and gumplant (Grin- 

 delia cuneijolia) . The foraging mannerisms seem quahtatively the 

 same as those characteristic of upland Savannah sparrows. On San 

 Pablo Marsh in late autumn to early spring many of the marsh 

 Savannahs work over the soft mud of the tidal sloughs, and some even 

 venture out to the very edge of the marsh fronting on the bay; here 

 they feed on small intertidal invertebrates, including the exceedingly 

 abundant small snails. There is a tendency for the birds to forage 

 together in loose flocks of perhaps 8 to 12 individuals at this time. 

 Thus there is some overlap in foraging beats of the Savannahs and 

 song sparrows of San Francisco Bay marshes. Yet the amount of 

 time the Savannah sparrows spend on the soft mud is small in com- 

 parison to that spent there by song sparrows. 



Distribution 



Range. — Resident on salicornia marshes and grasslands in the 

 coastal fog belt from Humboldt Bay, Humboldt County, to Morro 

 Bay, San Luis Obispo County, Calif. 



Egg dates. — California: 70 records, March 12 to June 15; 35 records, 

 April 1 to April 22. 



PASSERCULUS SANDWICHENSIS BELDINGI Ridgway 

 Belding's Savannah Sparrow 



PLATE 40 

 Contributed by Wendell Taber 



Habits 



In the prefatory remarks to his paper on the Savannah sparrows 

 of northwestern Mexico, Van Rossem (1947) made a particularly 



