Habitat Choice and Predator Avoidance in Tadpoles

Abstract

ABSTRACr.- Larvae of Ranidella signifera and Litoria ewingi are common members of tadpole communities of temporary ponds in southeastern Australia, where odonate larvae are the major predators. In field surveys, R. signifera was found more often on the pond substrate than was L. ewingi. This difference in habitat choice was documented further in laboratory aquaria, including a simulated pond edge. For both species, substrate use increased in the dark phase of a 12:12 photoperiod. In the laboratory, L. ewingi suffered heavier predation from the corduliid odonate Hemicordulia tau, a benthic predator, than did R. signifera. Predation on L. ewingi, but not on R. signifera, declined as water depth increased, implying that L. ewingi use the water column to escape benthic predators. Overall predation rate was greater in the dark phase when the predators were more active, and when tadpoles used the substrate more.