Home is where the hollow is: Revealing vertebrate tree hollow user biodiversity with eDNA metabarcoding

Tree hollows are essential for many vertebrate species, providing both nesting sites and shelter. Globally, old hollow-bearing trees are in decline resulting in many dependent species being under threat. It is therefore imperative that vital hollow-bearing trees are preserved, but it is logistically difficult to rapidly determine which hollows are being used and by which taxa. Here, we investigate the efficacy of eDNA metabarcoding as a survey tool for vertebrate hollow users. We compared the identity and richness of hollow-inhabiting vertebrate taxa using eDNA metabarcoding of both sediment from the tree hollows, and material collected using roller swabs. Samples (n = 138) were collected from hollow-bearing tuart trees (Eucalyptus gomphocephala; N = 28), within both an urban remnant and a relatively undisturbed forested area of South-West Western Australia. We detected a wide range of vertebrate taxa, including cryptic species such as the brush-tailed phascogale (Phascogale tapoatafa),...