A comparison of the flight initiation distances of male and female american bullfrogs (Lithobates catesbeianus) and green frogs (lithobates clamitans)

Comparing the escape responses of two similar species can help to reveal the underlying causes of different antipredatory responses. In this study, we compared the flight initiation distances of American Bullfrogs (Lithobates catesbeianus) and Green Frogs (Lithobates clamitans). We predicted that larger individuals would allow a predator to approach more closely than smaller individuals because larger individuals can jump further than smaller individuals. Therefore, we expected the smaller species, L. clamitans, to have a greater mean flight initiation distance than L. catesbeianus, and we expected females (which were the smaller sex in the study) to have a greater flight initiation distance than males. We tested these predictions using a model snake that was pulled by an electronic toy car. This is a novel method that may yield more accurate flight initiation distances than using an approaching human as the predator. We found that L. clamitans had a significantly greater mean flight initiation distance (17.8 cm) than L. catesbeianus (13.4 cm). We did not, however, find a significant difference between the flight initiation distances of males and females within either species. We also did not find a significant correlation between frog size (snout-vent length and mass) and flight initiation distance for either sex of either species