SONG SPARROW: SAN FRANCISCO BAY 1551 



less tinged with yellowish. Young much paler and grayer than that 

 of N. c. samuelis, with the broad black streaks on back and scapulars 

 much more strongly contrasted with the ground color; ground color 

 of under parts dull 3-ellowish white or pale yellowish buff, without 

 brownish tinge on breast or sides." — V.N.] 



Behavior: foraging. — Salt marsh song sparrows forage on the marshes 

 in the same fashion as do song sparrows in upland situations. Upland 

 races frequently scratch vigorously with their strong feet at the ground 

 surface to expose invertebrate and plant foods within and under the 

 surface litter. Salt marsh song sparrows perpetuate this foraging 

 mannerism; these birds scratch, typically with both feet in unison, on 

 the soft slough mud, and peck frequently at the disturbed surface. 

 One bird, for a period of 40 seconds, alternately scratched 3 to 6 

 seconds and pecked 1 to 5 times between each scratching period. 

 The bird was hunting small snails, and it furrowed and turned over 

 the top % 2 inch of mud covering about 8 square inches. Foraging on 

 harder mud comprising the true marsh surface most closely resembles 

 the scratching performed by song sparrows in upland habitats. The 

 birds also forage in "typical" fashion, i.e., slowly progressing by short 

 hops accompanied by wing flicks and tail flicks and punctuated by 

 frequent pecks at possible food items. 



Another type of foraging on soft mud could be called "terrestrial 

 flycatching." In midsummer on salt marshes large numbers of various 

 Diptera occur. Some of these frequent exposed mud at low tide, 

 flying just above the mud or resting on it. Song sparrows catch these 

 flies, by making short, jerky hops or runs with tail elevated and some- 

 times with wings half outstretched, but without leaving the ground. 

 Aerial flycatching is also a small part of foraging behavior in these 

 birds, but the half-outstretched wings are probably used to maintain 

 balance rather than to remain ready to resume flight. 



Salt marsh song sparrows feed at dried heads of the gumplant (a 

 composite) and eat the peeled seeds, perching on the edges of the larger 

 heads or on nearby stalks or heads. They look much like siskins or 

 goldfinches when foraging in this fashion. 



In autumn these song sparrows eat fleshy fruits and seeds of pickle- 

 weed or salicornia. The birds perch quietly in a patch of salicornia 

 and slowly and methodically chisel the fruits out of the succulent, 

 cylindrical spikes with their bills. They seem to prefer plants within 

 6 feet of the tidal sloughs, and they consume most of the available 

 fruits along the sloughs in 2 or 3 weeks, ordinarily at the end of Novem- 

 ber. This feeding is possibly of some importance as a source of free 

 water; it comes at a time when insect foods with their free water are 

 at an ebb. 



