EASTERN SAVANNAH SPARROW 691 



range dispersal from the breeding grounds occurs immediately. Tiie 

 first really large migratory movement begins in mid-September, with 

 the peak occurring from the last week of September to mid-October, 

 In the eastern populations the migration from north to south shows 

 a defuiite progression: Maine — September 15 to October 25; peak 

 period, end of September to October 13; Massachusetts and Rhode 

 Island — peak period from third week of September to second week of 

 October; Mar34and — September 15-25 to November 1-10, peak 

 period October 5 to October 30. The birds arrive on the wintering 

 grounds in North Carolina in late September, gradually increase 

 during October and become "commoner and more \\ddely distributed" 

 by early November (Norris and Hight, 1957). 



The Savannah sparrow is a nocturnal migrant, but in some instances 

 the migration may continue into the morning either as a manifestation 

 of continuing migratory restlessness, or as a redirected movement 

 away from the coast (Baird and Nisbet, 1960). The stimulus to 

 migrate in the fall is provided by the passage of the leading edge (cold 

 front) of a high pressure cell that, by late September and October, is 

 characterized by a sharp drop in temperature, fair strong north or 

 northwest winds, and clear skies. 



As with most small birds, the migratory period presents certain 

 hazards. Some are natural, but many are created by man. W. E. 

 Saunders (1907) reports on what may be considered a typical but in- 

 frequent natural migration disaster. An early snowstorm over Lake 

 Huron in western Ontario on the night of Oct. 10, 1906, killed thou- 

 sands of birds, of which Savannahs formed a small percentage. 

 Another natural disaster, which may take an annual toll far greater 

 than any recorded mortality, is the danger of being blown out to sea 

 (Scholander, 1955, and others). Savannahs have been recorded at 

 sea in both the Atlantic and the Pacific and, while some Savannah 

 populations fly over the ocean as part of their regular migration path, 

 as the Ne^vfoundland birds must, the evidence suggests that most 

 sightings of Savannahs at sea are of birds blown off course (Baird and 

 Nisbet, 1960). 



Man has long rivaled nature in his ability to cause mass mortalities 

 of migrating birds. Lighthouses were perhaps the fu'st of the man- 

 made structures to cause significant bird destruction, and have 

 presumably been doing so since they were first constructed. Savan- 

 nah sparrows have frequently appeared in the lists of birds killed 

 (Dutcher, 1884; Merriam, 1885). 



With the advent of ample electricity, the electric light, and the 

 increasing height of buildings, the lighted building became a beacon 

 of destruction under certain weather conditions, and continues to 



