Predator-prey dynamics have altered dramatically in Tasmania over the last two decades. The Tasmanian devil (Sarcophilus harrisii) has suffered a devastating disease, while there is evidence that eastern quoll (Dasyurus viverrinus) numbers have decreased and feral cat (Felis catus) numbers have increased as devils have declined. The red fox (Vulpes vulpes), which is a significant predator of native wildlife, has also been reported since the late 1990s.

DNA from predator scats constitutes a unique ecological resource and could provide critical information about predation by native versus introduced predators in Tasmania. In a metabarcoding approach, we have used Illumina paired-end sequencing to amplify 130-180 bp fragments of four mitochondrial genes (12S, 16S, COI and ND2) from 35 Tasmanian predator scats. In addition, four genomic DNA mixtures and 12 scats of known origin from captive animals (in some cases with known diet) were used to validate the approach. Primers were selected to primarily target vertebrate DNA, with a focus on native mammals, reptiles and birds. Over 15 million sequence reads were obtained: these were assigned to taxonomic groups with reference to public resources and a custom DNA sequence database of Tasmanian terrestrial vertebrates. We demonstrate that we can successfully detect predator and prey DNA from scats of unknown age collected in field conditions and stored for up to 5 years. An improved understanding of the impact of introduced predators on native species will contribute to wildlife management plans in Tasmania and elsewhere.