Continuous daily sampling of airborne eDNA detects all vertebrate species identified by camera traps

Abstract

Ongoing pressures on global biodiversity require conservation action that is not possible without effective biomonitoring. Terrestrial vertebrate surveys are commonly performed using camera traps, a time-intensive method known to miss many small or arboreal species and birds. Recent advances have shown airborne eDNA to be a potentially suitable technique to more effectively monitor vertebrate communities in a time- and cost-effective manner. Here, we test whether commercially available air samplers that collect air particles 24/7 during a 1-week period can be used to detect the presence of vertebrates through airborne eDNA. The results are compared to camera trap records at three locations with differing habitats in the Netherlands. Simultaneous sampling with three different air samplers for 3 weeks resulted in detection of 154 vertebrate taxa, of which the majority were birds or mammals (113 and 33 species, respectively), along with four fish and four amphibian species. All species observed using camera traps were also retrieved via airborne eDNA, although not on every day of sampling. The Burkard spore trap, used routinely for pollen monitoring, showed the highest number of vertebrate species, and only in three samples when a mammal species was detected using a camera trap it remained undetected via eDNA. We also detected unique species at the three locations using airborne eDNA, indicative of the habitat in which they were living. However, we also detected species that we could not account for. The multitude of species found using airborne eDNA compared to camera traps indicate the sensitivity of the method; however, subsequent studies should prioritize validation of these findings through alternative biomonitoring approaches.