Reviving Ecological Functioning with Dingo Restoration

A project undertaken at the School of Marine & Tropical Biology, James Cook University, and supervised by Arian Wallach and Chris Johnson

"A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise" Aldo Leopold

Almost half of all mammalian extinctions worldwide in the past 200 years have occurred in Australia. This crisis has been directly attributed to the introduction and spread of alien invasive species. Ecosystem restoration is a growing field dedicated to the rehabilitation of degraded environments. In Australia this has taken the form of widespread pest control and reintroduction programs of endangered species. Both actions focus on the weaknesses in the ecosystem, and thus we believe that they cannot be sustainable solutions. We propose an alternative working model for ecological restoration which focuses on restoring the inherent strengths of ecosystems.

Our basic concept follows an acceptance that once an exotic species has successfully established itself on a mainland environment or large island it cannot be eradicated and should not be controlled by conventional means. Instead, we should look for methods which enable native species to persist alongside invasives by promoting the inherent strengths that enable ecosystems to maintain resilience to change. We believe that this approach will provide a solution to the problem of mammalian invaders in Australia, through the restoration and conservation of a top-order predator.

Top-order predators have been recognized as keystone species in virtually all terrestrial and marine ecosystems worldwide. Their decline has been linked to secondary extinctions and their increase to ecological restoration. These processes are attributed to the ecological role of large predators as suppressors of medium sized predators (mesopredators) and herbivores. Following the loss of top predators, mesopredators and herbivores are released from top-down regulation leading to biodiversity loss. The ecological importance of top predators has therefore been the focus of extensive research worldwide. However, this topic has only recently emerged in Australia as a potential mechanism for biodiversity conservation.

Several studies have documented that dingoes control invasive mesopredators and generalist herbivores, and are positively correlated with the persistence of native species. Since European occupation, dingoes have been targeted for lethal control over much of the continent. The pastoral industry regards the dingo as a threat to livestock, particularly to sheep production. Conservation agencies also afford dingoes little or no protection and often actively control them to reduce their impact on neighboring pastoral stations. Some consider the dingo a threat to native wildlife and an introduced pest. Considering the potential key role of dingoes in biodiversity conservation, such intensive persecution over the past 200 years may explain why Australia has lost so much of its biodiversity.

Using both an experimental and macroecological approach we aim to test the following hypotheses:

1. Dingoes reduce and stabilize cat, fox, rabbitand large herbivore abundance;
2. Dingoes cause an increase in abundance and diversity of small native mammals;
3. Through ecological cascade dingoes increase vegetation recruitment and
   diversity;
4. The social integrity of dingo populations is a major factor in their ecological functioning; and
5. Threatened species only survive in the presence of dingoes.

The experimental component of this study tests whether the restoration of dingoes, via cessation of poison baiting, results in ecosystem restoration. The macroecological component investigates whether the presence of abundant and stable dingo packs is a correlated with the persistence of threatened species on a continental scale.

The work conducted so far has provided encouraging results on the potential benefits of dingo conservation for ecological restoration. Perhaps one of the greatest advantages of this approach is that human intervention can be relaxed, allowing natural processes to take over. The preliminary results of this study and the available information on top-down regulation worldwide highlight the importance of furthering our knowledge in this field in Australia.