The diet of introduced cats on San Cristobal Island, Galapagos: cat feces as a proxy for cat predation

Introduced cats (Felis catus) are one of the most serious threats to the native fauna of the Galapagos Islands, yet information about their impact on local species is still scarce. Studies from the 1980s indicate that the main prey items that make up the diets of introduced cats in the Galapagos include reptiles such as lava lizards and iguanas, land and marine birds, introduced mice and rats and several invertebrate species. In this study analyses of 132 cat fecal samples from San Cristobal Island confirmed the presence of mice, rats, invertebrates and lava lizards in the diet of feral cats; lava lizards being the most consumed prey. In the same analysis, we found a strong positive correlation between the number of cat feces and the number of lizards, mice and rats preyed upon by cats, which might indicate that cat feces could be used as an alternative tool to assess the level of cat predation in an area. Information on the dietary patterns of the introduced cats in the Galapagos might contribute to the development and improvement of conservation strategies to control or eradicate this invasive species on the islands and thus protect the endemic and emblematic species they prey on.