DNA metabarcoding improves detection of rare and volant prey in the diet of feral cats (Felis catus)

Abstract

Context Cats (Felis catus) have contributed to the extinctions of more than 60 vertebrates and continue to be a major conservation threat globally. Conservation managers traditionally record the diet of cats from morphological (manual) searches of stomach or scat samples. However, prey items can be missed due to the rapid digestion and degradation of soft tissue. Aims We aimed to compare the effectiveness of morphological and molecular diet analysis, with a specific focus on whether some taxa are not being detected due to the methodology, including bats (Chiroptera). Methods We used a novel application of molecular methods (DNA metabarcoding) to analyse cat stomachs, rather than scats, collected around two Australian arid-zone conservation reserves and compared this to morphological searches at one of these sites. Key results Molecular analysis detected twice the species richness of morphological methods and higher frequency of occurrence (%) for mammals and birds, though it did not detect any Ctenophorus (dragons). Conclusions Our results highlight that morphological analysis alone likely under-represents the true assemblage and occurrence of prey taxa particularly for birds and rare species and, where feasible, should be complemented by molecular analysis. We found no evidence of bat predation at our arid study sites, consistent with longer-term morphological cat stomach data. Implications Overall, these findings have direct implications for invasive predator monitoring programs, as detection of rare species is crucial to effective monitoring and conservation. Furthermore, additional monitoring at known roosts and in drier periods could improve our knowledge of cat predation on bats.