MIGRATION AND SEX RECOGNITION IN FROGS 



331 



Migration occurred both during day and night. For the period 

 including March 26th through April 2nd, the time of concen- 

 trated migration, table 2 shows an equal distribution of day and 

 night migrations, the totals including both sexes of the four 

 species. The numbers of individuals of any one species or sex 

 are too small to admit of further conclusions, except that night 

 time seems to be more favorable for the migration of the wood 

 frog and spring peeper. It appears, then, that the inciting 



TABLE 2 



Showing, separately for each sex of the four species, the day and night distribution 

 of migrations between March 26th and April 2nd, inclusive 



stimulus for migration and the factors controlling the migration 

 behavior operate independent of light and darkness. 



Temperature was an important factor in the control of mi- 

 gration. No catches were made in the period between April 

 3rd and April 14th, inclusive, a time when the thermometer was 

 low. The lowest temperature accompanied by migration was 

 33.6° F., and only two frogs were trapped on that date. The 

 largest catches were made between 41° and 52° F., this range 

 indicating an optimum temperature. No temperatures were 

 high enough to determine a maximum. 



