40 



BLACK AND WHITE WARBLER 



Spring Migration. A few Black and White Warblers winter in 

 southern Florida, so that the only way of knowing the beginnings 

 of spring migration in that district is from the records of the striking 

 of the birds at the lighthouses. Both at Alligator Reef and at Som- 

 brero Key lighthouses in southern Florida, this species begins to 

 strike early in March. Thence, northward the progress is so slow 

 an average of twenty miles per day that it is the middle of May 

 before the species has reached the Gulf of St. Lawrence. 



