Development and deployment of samplers
Location of sampling was selected for its confirmed long-term koala presence (Cardno 2020). In parallel to the deployment of the airborne eDNA filters, targeted fauna surveys were undertaken to identify koala presence and record their GPS location(s). We designed two types of air filtering sample collection systems which were fitted with sterile cheesecloth for the collection of airborne eDNA. The first air sampling system was composed of a vertical air sampler which allowed for a flow rate of 0.8m/min powered by a waterproof lithium battery pack. This first system was then stationed elevated at approximately 60 cm above ground by securing it to star pickets. The second air sampling system was simply composed of a sterile cheesecloth filter set between sterile stainless-steel plates and attached to the start pickets facing upright in a horizontal position. These two sampling systems were deployed across 11 sites for 72 hours. All equipment used in the deployment and collection of samples was either purchased gamma sterilised and for single use (e.g., storage tubes) or washed with a bleach solution and autoclaved prior to use (e.g., stainless steel plates). Samples were collected under the animal ethics number 2022/AE000765 from the University of Queensland.