Comparative feeding behaviour of native and introduced terrestrial snails tracks their ecological impacts

A developing body of theory and empirical evidence suggest that feeding behaviour as measured by the functional response (FR) can assist researchers in assessing the relative potential ecological impacts and competitive abilities of native and introduced species. Here, we explored the FRs of two land snails that occur in SW Ontario, one native (Mesodon thyroidus) and one non-indigenous (Cepaea nemoralis) to Canada. The non-indigenous species appears to have low ecological impact and inferior competitive abilities. Consistent with theory, while both species conformed to Type II functional responses, the native species had a significantly higher attack rate (5.30 vs 0.41, respectively) and slightly lower handling time (0.020 vs. 0.023), and hence a higher maximum feeding rate (50.0 vs 43.5). The non-indigenous species exhibited a significantly longer time to contact for a variety of food types, and appeared less discriminating of paper that was offered as a non-food type. The non-indigen...