NNW 



WIND 

 N 



NNE 



NW 



NE 



WNW 



ENE 



W 



wsw 



ES£ 



SW 



SE 



SSW SSE 

 S 



MIGRATION 



NNW 



N 



NNE 



NW 



NE 



WNW 



ENE 



W 



WSW 



SW 



ESE 



SE 



SSW 



SSE 



Fig. 26. Wind Direction and Migration to Large Totteridge 



over the Road 



The wind diagram shows the frequency of the winds over the period, the 

 length of the hnes being in proportion to the frequencies at each direction. 

 Note that there were no south-east winds in this period. The migration 

 diagram shows, on the same scale, the amount of migration, that took place 

 when the wind was blowing in the indicated direction. If these frogs had 

 migrated at random, this diagram would be the same as the wind diagram. 

 It is clearly quite different, showing a large excess of migration when the 

 wind was in the southerly direction, that is, blowing across the pond to 



the road. 



