Behavioral responses of anuran larvae to chemical cues of native and introduced predators in the Pacific Northwestern United States

Abstract/Summary

We compared behavioral responses of three Pacific Northwest anuran larvae from different hydroperiods to water born cues of native and introduced predators. Two native anurans (Pacific treefrog, Pseudacris regilla and northern red-legged frog, Rana aurora aurora) and introduced bullfrogs (Rana catesbeiana) responded to water conditioned by native redside shiners (Richardsonius balteatus) by increasing refuge use. The two native anuran larvae differed in their response to introduced predator cues. Rana a. aurora, which occur in temporary and permanent waters, responded to both introduced bluegill sunfish (Lepomis macrochirus) and introduced crayfish (Procambarus clarkii). Pseudacris regilla, which occur primarily in temporary ponds, did not respond to water born cues from either introduced predator. The broader responses of R. a. aurora may indicate greater behavioral plasticity or more exposure to novel predators than experienced by P. regilla. Larvae of introduced R. catesbeiana responded strongly to cues from two fish native to the Pacific northwest, but did not alter behavior in response to any of five potential predators with which they co-occur in their native range. Fish that occur with R. catesbeiana in their native range generally find bullfrog tadpoles unpalatable. This pattern suggests that bullfrog larvae can recognize cues of novel predators that may find them palatable, which could contribute to their success as an invasive species in the region.