NORTHERN SEASIDE SPARROW 821 



The chase is not vigorous, and fighting is minimal, for occupancy is 

 widely respected and almost invariably the intruder flees. 



My study area in New Jersey, a marsh islet approximately 1,400 

 feet long and 600 feet wide, supported eight pairs of seaside sparrows 

 in 1955. The territory of each pair consisted of a nesting area in the 

 thicker sedges or bushy growth within the marsh, and a feeding area 

 in the more scattered cord-grass (Spartina) and open mud at the marsh 

 edge. The two were contiguous in some cases; in others they were 

 separated by several hundred feet of marsh that the birds flew across 

 and seldom alighted in. I never saw the species forage in the interior 

 of the marsh, but each pair fed within a particular segment of shore- 

 line usually not more than 200 feet in length and scarcely 20 feet wide. 

 All parts of the territories of the different pairs were mutually exclusive, 

 and in 6 weeks of close observation of marked birds (June 15 to August 

 1), I saw no resident seaside sparrow outside its defended area, which 

 in no case extended more than 400 feet in any one direction. 



No population density studies of the seaside sparrow have been 

 conducted in large tracts of optimum habitat. In Maryland, Springer 

 and Stewart (1948) found two territorial males in 19.5 acres (lOp/100) 

 of a salt marsh bulrush {Scirpus robustus) — saltgrass (Disfichlis spicata) 

 marsh and two territorial males in 22.25 acres (9p/100) of needlerush 

 (Juncus roemerianus) marsh. The ditched islet I studied in New 

 Jersey had 8.25 acres of marsh (the remainder was sand fill) domi- 

 nated by smooth cord-grass (Spartina alterniflora) , black grass (Juncus 

 gerardi), and rows of marsh-elder (Ivafrutescens). Each of the eight 

 occupied territories here contained portions of the open mud shoreline 

 where the birds fed. A larger tract of similar habitat would not have 

 so dense a population (97p/100) because it would possess relatively 

 less open shoreline. 



Nothing is known of courtship and pair formation in this species. 

 When I began intensive observations on June 15, all nests already 

 contained eggs. In late June an influx of unhanded birds occurred, 

 apparently individuals that had not yet nested or had perhaps nested 

 unsuccessfully elsewhere. A few of these established territories in 

 marsh unoccupied by the remaining original residents. On July 7 I 

 watched one of these females as she seemed to be searching for a nest 

 site. She crawled about in a marsh-elder bush, apparently testing the 

 various forks in the branches for size. The male followed, remaming 

 a few inches above and behind her. Several times the two birds dis- 

 appeared in the lower branches where they were hidden by the sur- 

 rounding black grass. Finally while the female squatted on a branch 

 the male fluttered his wings, mounted on her back, and continued 

 fluttering his wings during the few seconds of supposed copulation. 



