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



Nesting. — In contrast to the sharp-tailed sparrow which prefers the 

 higher and drier parts of the marsh, the seaside sparrow ahnost always 

 nests in the wetter portions (Stone, 1937; Forbush and May, 1939; 

 Cruickshank, 1942). It usually builds just above the normal summer 

 high tide mark where black grass {Juncus gerardi) and smooth cord 

 grass (Spartina alternijlora) are the dominant plant growth. Most of 

 the salt marshes in New Jersey have been ditched for mosquito control. 

 On the mounds of excavated muck along these narrow ditches grow 

 rows of marsh-elders {Iva frutescens) which provide suitable, often 

 preferred nesting sites for the seasides. 



Of the eight nests I found in 1955, four were supported by marsh- 

 elders (three of them dead), three were built in black grass tussocks, 

 and the eighth was supported mainly by cord grass stems. All eight 

 nests were simple open cups built entirely of black grass stems and well 

 concealed in the black grass, which grew so thickly around them they 

 could be entered from only one direction. The prevailing southwest 

 winds of spring and summer lean the marsh grass to the northeast, and 

 six of the nests were approached from the easterly quadrant. Two 

 nests, built in marsh-elders that held the surrounding grass stems 

 upright, were entered from the northwest. One nest, built in a small 

 dead marsh-elder, was soon tilted by the growth of the black grass 

 supporting one side. Though this did not spill the contents, the 

 adults shortly deserted the nest. 



From the ground to the upper rim the eight nests varied from 9 to 

 11 (average 9.6) inches. Their outside diameters ranged from 3 to 

 4.5 (average 3.9) inches, and outside depths from 2 to 3.5 (average 2.7) 

 inches. Inside diameters varied between 2 and 2.5 inches; seven nests 

 had an inside depth of 1.5 inches, the other only 1 inch. 



Eggs. — The seaside sparrow lays three to six eggs, with four or five 

 comprising the usual set. They are ovate and have only a slight 

 gloss. The ground is white or pale greenish-white, profusely speckled, 

 spotted, and blotched with dark reddish browns such as "Hay's 

 brown," "burnt umber," "Mars brown," "Front's brown," or "auburn," 

 and with underlying spots of "light purpUsh gray." The markings 

 are usually well defined and tend to be concentrated toward the 

 large end. On some the undermarkings are quite prominent, on 

 others entirely lacking. In series the eggs are noticeably larger than 

 those of the sharp-tailed sparrow, and their markings are generally 

 larger and bolder. The measurements of 50 eggs of the nominate 

 race average 20.9 by 15.5 millimeters; the eggs showing the four 

 extremes measure 22.9 by 15.8, 20.3 by 16.6, 18.3 by 15.2, and 22.1 

 hj 14-5 millimeters. 



Incubation. — The birds I studied in 1955 raised only one brood that 

 summer, and the egg dates suggest that the northern seaside sparrow is 



