Modified Interactions between Salamander Life Stages Caused by Wildfire-induced Sedimentation

A 1993 wildfire and subsequent landslides modified many streams in the Santa Monica Mountains of southern California (USA). Prior to the fire at Cold Creek Canyon, adult California newts (Taricha torosa) frequently preyed on conspecific eggs and larvae. Post-fire landslides increased the number of stream pools containing terrestrial earthworms. Earthworms were more common in adult newt diets after the fire, and conspecifics were absent. More earthworms and fewer conspecifics were present in the stomachs of adult newts in streams at burned sites than at unburned sites. In laboratory experiments, newt larvae used refuges significantly less in the presence of combined chemical cues from both newt adults and earthworms as compared to adult-newt cues alone. These data suggest that cannibalism is reduced in the presence of increased alternative prey items and that larvae can detect this reduced predation risk.