Developing eDNA monitoring

For the last year we have been developing a novel monitoring technique that is designed to monitor the occupancy rate and population health of hard-to-find lizard species using environmental DNA (eDNA) tracking. Our technique involves collecting eDNA from lizards in a non-invasive way. We place pipes containing filter paper in lizard habitat, when the lizards move through these pipes, they leave traces of eDNA that can be analysed. The pipes are placed across a habitat to gain an understanding of general occupancy (see below for detailed information on occupancy). Our method is non-invasive, less labour and expertise intensive and potentially more cost-effective than existing techniques which typically involve physical capture, visual sightings, or electronic devices that are prone to failure.

In autumn 2023, Southern Lakes Sanctuary completed the first trial of this technique at the Mokomoko Dryland Sanctuary on endangered Otago skinks (Oligosoma otagense) which are notoriously difficult to monitor. The preliminary results suggest that we have a valid method for detecting cryptic lizards in these environments and an indication on the best timeframe for leaving eDNA pipes in the habitat. Given that many lizards in New Zealand are threatened with extinction, and there is a lack of low-cost, non-invasive monitoring methods, this eDNA-occupancy technique could be ground-breaking both on the national and global scale. To develop the technique further, a small trial is proposed in the Mokomoko Sanctuary to see whether we can enhance detection rates using baited pipes. A full-scale occupancy survey on an endangered cryptic skink species in complex habitat will then be completed to see how the technique performs out of the managed area.