Feeding Ecology and Range Expansion of the Nonnative Italian Wall Lizard (Podarcis sicula)

The Italian Wall Lizard, Podarcis sicula, is an opportunistic, omnivorous lizard native to Italy and the east Adriatic coast. Multiple introduced populations of this species occur in the Mediterranean region, and P. sicula was also introduced to an urban Southern California neighborhood in 1994. Over a 14 month period, we conducted regular field surveys to track changes in range of the nonnative Southern California population. We also examined the feeding ecology of California P. sicula to assess dietary overlap with native lizard species and the effects P. sicula is having on co-occurring species. During the survey period, considerable range expansion was observed. Further, the gut analyses demonstrate dietary overlap with the native Western Fence Lizard, Sceloporus occidentalis, and Southern Alligator Lizard, Elgaria multicarinata, which also occur in this neighborhood. Podarcis sicula were found to cannibalize smaller individuals, suggesting that predation upon native lizards is also likely. Few native lizards were observed sympatrically with P. sicula suggesting that direct competition and/or predation could be causing localized declines of these native lizards.