40 BIRDS OF SOUTH DAKOTA 



becoming confused and flying low, often perish by dashing 

 themselves against monuments, light houses, telegraph poles 

 and wires and even the sides of buildings. It is stated upon the 

 best authority that "over 1,500 birds have been found dead at the 

 base of the Bartholdi statue in New York harbor in a single 

 morning, and 230 birds of one species (Black-poll Warblers) 

 were killed in a single night by the Fire Island Light. The 

 Washington monument, though not illuminated at night, causes 

 the death of hundreds of birds annually." 



Looking through a telescope focused on the moon during 

 migrations, the observer sees many birds cross the moon's disc. 

 In this way the direction is noted, their height calculated, and 

 often even the species recognized. The multitude of feathered 

 migrants that fill the air at such times may be discovered, at 

 least in part, by counting the calls as the birds pass. 



The writer stood one evening in early September on the 

 shore of Pickerel Lake, in South Dakota, and watched the pass- 

 ing of Franklin's Gulls. They flew southward in great streams. 

 When one stream had passed, and what seemed a few belated 

 stragglers were hurrying forward, another stream would appear 

 in the distance, then another, and another. For half an hour he 

 watched them and wondered if there was to be no end. A year 

 later, and within a few days of the former date, he witnessed 

 the same beautiful sight a second time. 



So regular are the seasonal conditions, so constant also 

 is the habit of most birds, that any one who observes dates can 

 tell within a few days when any bird will appear. 



A sudden drop of temperature during spring migration 

 will often cause birds which otherwise would pass on, to remain 

 about for days. Black Terns have been known to linger even for 

 weeks as though settled for the summer. A pleasant autumn 

 also will retard the fall migrations of many of the feathered folk, 

 especially those that come north early in the spring, and do not 

 winter far south. In ordinary seasons and weather, however, 

 as stated above, the migration of birds is surprisingly regular. 



The males of most species arrive a few days ahead of the 

 females. Male House Wrens will carry sticks into three or four 



