1913 ' I Cooke, The Relation of Bird Migration to the Weather. 209 



The birds came three or more days 



early with a cold temperature 42 



late " " warm " 41 



early " " normal " 29 



late " " " " 23 



Arrivals do not agree with theory 135 



The above figures show that in the case of the more pronounced 

 variations, the arrival seems to have been hastened by warm 

 w r eather or delayed by cold in only 125 instances out of 260, or only 

 48 percent. 



The smaller variations show still less dependence of movement on 

 warmth. 



Bird arrivals at Lanesboro, Mian., 1885-1898. 



No. of 



The birds came one or two days Instances. 



early with a warm temperature 47 



late with a cold temperature 38 



Arrivals agree with theory 85 



The birds came one or two days 



early with a cold temperature 28 



late with a warm temperature 43 



early with normal temperature 18 



late with normal temperature 23 



The birds came on time with a cold temperature 15 



" " " " " warm temperature 21 



Arrivals do not agree with theory 148 



Here is no evidence at all that the temperature has either stimu- 

 lated or retarded bird migration. 



A slight connection may be noted by comparing the total num- 

 ber of arrivals in warm and in cold weather. During the spring 

 days of these nine years, when the temperature was above the 

 normal, 2 13 arrivals of birds wore noted, and when the temperature 

 dropped below the normal, only 1>S2 birds were recorded as arriving. 

 This shows that whether or not the warm weather causes them to 

 come earlier, they prefer on the average to advance when the 

 weather is warmer than normal. 



