When Fleeing Matters: Differences in Escape Behaviours of Three Northeast Asian Anurans

Prey species may have their own optimal escape strategy to balance predation risks and the energetic cost of fleeing. Some species have an advantage when maintaining a short fleeing distance, while others may favour an earlier escape based on microhabitat, size, or body condition. Here, we examined the escape behaviour of the three syntopic Northeast Asian anuran species: Mongolian toads (Strauchbufo raddei), Amur brown frogs (Rana amurensis), and Japanese treefrogs (Dryophytes japonicus) in Mongolia, Russia, China and DPR Korea. We examined flight initiation distance (FID; the distance from a potential predator to the point when the individual starts to flee) and distance fled (DF; distance between flight initiation and flight termination points) of each species and the effects of microhabitat, sex, and body size. Strauchbufo raddei and R. amurensis had a longer FID than D. japonicus, and S. raddei also had a longer DF than D. japonicus. These trends remained similar when dividing FID and DF by a size proxy (snout-vent length) for all individuals. This suggests that the treefrog D. japonicus used a strategy to stay immobile even when they were detected, and the toad S. raddei reacted quicker and more sensitively to predators despite the presence of toxin. Female S. raddei had a significantly longer FID than males suggesting that females are more sensitive to predation risk in this species, but body size was not significant for any of the three species. Our results indicate that the three sympatric species have different escaping strategies, likely related to differences in physiology and crypticity.