The Great Poo Hunt: A comprehensive DNA-based predator scat survey conducted in Tasmania, Australia.

Abstract

Understanding how mammal populations interact with each other and their immediate environment is of critical importance to predicting responses to environmental change while knowledge on diet and distribution of emerging invasive species is vital to management efforts. However, estimating species distributions, let alone interactions among them, has remained problematic through the technical limitations of sampling mammals broadly across landscapes. Here, we report the conduct of a comprehensive systematic predator scat survey in eastern Tasmania aimed at providing spatial and temporal data on the distributions of key mammalian predators and their prey. This approach has been made possible through the application of next generation sequencing approaches to the analysis of trace DNA material obtained from the scats. The 2014 survey is a follow up to a previous survey conducted by DPIPWE’s fox eradication program during 2008-2010. We have collected scats from approximately 300 survey units distributed systematically across the eastern part of Tasmania in Agricultural and Urban environments and Native Grasslands. Each 3km x 3km unit was surveyed for ten person hours using staff and volunteers. Search efforts concentrated on landscape features, such as tracks, fence lines and dam walls, used by predators to navigate through the environment. Scats were collected in paper bags on site using rigorous guidelines to minimise the risk of contamination and maintain the integrity of the samples. Full habitat and locational data were also collected. Dried scats have been sent to the University of Canberra’s specialised trace DNA laboratory for analysis (please refer to Elodie Modave’s poster for further information on analysis). Next generation sequencing of amplified products from each scat will be used to identify the likely predator that passed the scat, and the prey DNA contained within it. We have collected over 4,000 scats during two time periods (2008/09 and 2014): these will be used to infer predator prey interactions in Tasmania and show any changes that may be occurring across time. This information will contribute to the current management of invasive predators and their prey and the understanding of ecosystem change.