RAPIDITY OF MIGRATION MOVEMENT in 



than those that leave their winter quarters earlier in 

 the year. 



Part of our black and white warblers (Mniotilta 

 varia) winter in Florida and southern Texas, but the 

 majority pass on to the West Indies, Mexico, and 

 northern South America. Migrants on their way 

 north are recorded at the lighthouses of southern 

 Florida about March 4, but migration does not ex- 

 tend beyond the northern limit of the winter range 

 into southern Georgia until about March 24, so that 

 these early migrants travel at an average rate of 

 only 20 miles per day through this area. Between 

 southern Texas and northern North Dakota, this 

 bird averages about 22 miles per day, but from that 

 point north to the limit of the breeding range the 

 rate of speed is almost doubled. 



The gray-cheeked thrush, on the other hand, 

 which does not reach the southern United States 

 from its winter home in South America until late in 

 April, arrives a month later in extreme northwestern 

 Alaska, so that it covers a 4000-mile journey on this 

 continent at an average rate of 130 miles per day. 



Professor Cooke has figured the average speed for 

 small birds in general in passing up the Mississippi 

 Valley at 23 miles per day. In addition to the species 

 that have been mentioned he gives some interesting 

 figures for a few others. The black-poll warbler, in 

 its northern flight from South America, arrives on 



