Insects were shown to be of minor importance in the Patuxent 

 sample, constituting only 5 percent of the total food. (H.D.) 



Keywords: birds, food habits, coastal marsh, Maryland 



V-B-38 



Johnston, R.F. 1956. Population structure in salt marsh song sparrows; 

 part I: environment and annual cycle. Condor 58:24-44. 



A population study of song sparrows, Melospiza melodia samuelis , 

 was conducted from 1950 to 1955 on San Pablo marsh, California. 

 A total of 287 individuals were color-banded. 



San Pablo marsh is a typical San Francisco Bay salt marsh, grown 



to a Spartina association on lower levels and a Salicornia association 



on higher ground. The tidal range is -2.5 to 9.0 feet; mean higher 

 high water is 5.8 feet. 



The most important food of the song sparrow is the invertebrate 

 fauna associated with marsh vegetation. Factors influencing the 

 initiation of breeding include the photo period, temperature of the 

 preceding three months, and the amount and distribution of the winter 

 rainfall. These factors also affect the amount and quality of the 

 sparrow's food supply. (B.W.) 



Keywords: sparrows, salt marshes, population structure, San Francisco Bay 



V-B-39 



Johnston, R.F. 1956. Population structure in salt marsh song sparrows; 

 part II: density, age structure, and maintenance. Condor 58:254-272. 



On the study plot on San Pablo marsh, song sparrows in a year of 

 medium density numbered approximately one pair per acre. Along the 

 sloughs the density ranged from six to ten pair per acre, depending 

 on the absolute number of birds on the marsh and the complexity of 

 the vegetation available. Density was found to vary directly in relation 

 to the preceding year's productivity. 



Mortality factors include rodent predation, high tide water, death 

 of or desertion by the adults, infertility and embryonic death, and 

 storms. 



Those aspects of the population that favor a strong isolation, a 

 high population density, and the existence of habitat selection by the 



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