A project undertaken at The University of New South Wales, and supervised by Dr Neil Jordan.
Nest predation by mammals is a key threat to many native Australian species in several contexts, including for ground-nesting birds (e.g. endangered mallee fowl and plains-wanderer), tree-nesting birds (e.g. critically endangered regents honeyeater), beach-nesting reptiles (e.g. endangered loggerhead sea turtle), and threatened shorebirds (e.g. endangered pied oystercatcher and critically endangered Eastern Hooded Dotterel). While current management approaches to control these threats rely on predator removal, this is expensive, labour-intensive, and often fails to completely remove the threat. Indeed, a single fox that evades control efforts can wipe out the entire annual breeding output of a shorebird colony and negate the significant investments in prior conservation management. Additionally, the management intervention itself can result in the need for further costly interventions. One such example of this is where apex predators – such as dingoes – are removed. This has the potential to undermine pack structures and trophic interactions, potentially increasing the population of– and overall threat from – invasive foxes – thereby increasing the challenge, scale and overall cost of pest management. Ultimately, tools are needed that allow the retention of native predators in the ecosystem, while protecting native threatened species from direct predation and disturbance on a more localized scale.
This project will develop and test a portable ultrasonic deterrent device that can be deployed in these contexts. Ultrasonic deterrents emit signals between 15-25Hz – i.e. within the hearing range of mammals but beyond that of birds. This offers the possibility to deter mammals from nest sites without affecting the birds themselves. We will conduct a series of field experiments to: 1) Test whether ultrasonic deterrents have an aversive impact on mammalian predators (foxes, feral cats, dingoes). Camera-traps will be used to determine the detection likelihood (and responses of) of the carnivore species when ultrasonics are being played versus control periods; 2) Confirm that ultrasonic deterrents have no aversive impact on shorebirds by playing calls to free-ranging shorebirds outside of their breeding season and observing their responses; 3) Determine the effective aversive distance for target species; 4) Evaluate the efficacy of ultrasonic deterrents in preventing predator incursions and disturbance to active nest sites, and ultimately increasing breeding success. As such, this study will provide critical in situ field tests of a potential management tool that can be used across a range of contexts to reduce nest predation and disturbance – thereby addressing key threats to the viability of several threatened species while reducing the costs and negative consequences of lethal dingo control.
