BIRDS OF ESSEX COUNTY. I 79 



The female Semipalmated Sandpiper has a distinctly longer bill than the 

 male. The average of the bills of thirteen adult males measured by me is 0.73. 

 and of ten adult females 0.81 of an inch. The young birds can be distinguished 

 by their nearly white breasts washed with a smoky tint. The field marks which 

 distinguish this bird from the Least Sandpiper are given under that species. 



109 [247] Ereunetes occidentalis Lawr. 

 Western Semipalmated Sandpiper. 



Rare autumn transient visitor ; August 29 to September 20. 



How commonly this bird occurs, one cannot say, for in autumn plumage it 

 can hardly be distinguished from the eastern species except by the bill which is 

 longer, a difference so slight that the gunner never discriminates. Of three 

 male birds measured by me, two taken at Magnolia and one at Ipswich, the 

 bills measured 0.92, 1.05, and 0.95 inches, respectively. The last was a young 

 bird of the year. In adult females the bill might reach 1.20 inches. 



no [248] Calidris arenaria (Linn.). 

 Sanderling; "Beach-bird"; "Whitey"; "Beach Plover." 



Abundant transient visitor; May 20 to June 4; July 10 to November 19 

 (December 6). 



The Sanderling is one of the latest shore birds to leave in the fall. I have 

 several times found them in November, and once, in 1903, I found a single bird 

 as late as December 6th. It is essentially a bird of the beaches, and keeps as 

 close to the water's edge as possible, eagerly following in crowded ranks the 

 receding wave and running nimbly before the advancing one, gleaning most dili- 

 gently the abundant food to be found there and probing vigorously the sand. I 

 have never seen it in the large marshes although occasionally single birds visit 

 the sloughs at Eagle Hill. It is often very tame and unsuspicious, especially 

 the young birds. Flocks will sometimes return to the gunner's decoys after 

 each shot until all are slain. 



Sanderlings are sometimes found in flocks of other shore birds, although 

 usually they keep by themselves in flocks of from three or four up to thirty or 

 more. They are rather silent, but generally emit a sharp sight or squeaking 



