In this chapter, we outline the research conducted on vertebrates at the two sanctuaries. There are two main groups of vertebrate species in the sanctuary: those in situ at the Experiment’s outset (e.g., macropods, birds and herpetofauna) and reintroduced species (e.g., eastern quoll and New Holland mouse). Our research on macropods at the sanctuaries examines their grazing impacts on biodiversity and highlights management strategies, including the application of fertility control to maintain sustainable populations. Our research on herpetofauna, such as skinks and frogs, reveals the critical role of coarse woody debris (CWD) in enhancing reptile habitat and has highlighted frogs’ sensitivity to climate-driven droughts. Long-term bird monitoring in the experiment has shown significant declines in small woodland species, attributed in part to competition from the aggressive noisy miner. Reintroduction trials for the eastern quoll and New Holland mouse demonstrate the value of adaptive management and novel strategies such as Mini Safe Havens to promote population persistence of rare species.

This chapter presents the reintroduction biology of the eastern bettong (Bettongia gaimardi) at Mulligans Flat Woodland Sanctuary (MFWS), detailing strategies, tactics, and outcomes across establishment, growth and regulation phases. Adaptive management guided translocation planning, health monitoring and post-release assessments. Immediate-release tactics proved more effective than delayed-release, with high survival and reproductive success. Physiological stress, body condition and genetic diversity were tracked, revealing improved health and stable population dynamics. The population reached density dependence within six years, indicating successful regulation. Genetic monitoring confirmed retention of source diversity and highlighted the need for long-term sampling. A trial reintroduction beyond predator-proof fencing tested coexistence with invasive predators, introducing the ‘Goldilocks Zone’ concept for adaptive predator exposure. The chapter proposes ‘coexistence conservation’ as a long-term strategy to restore native species in landscapes where eradication of invasive predators is unfeasible, emphasising evolutionary adaptation and multi-stage trials.

Chapter 4 considers how duties of international cooperation safeguard sovereign equality by reconciling the territorial sovereignty of coastal states with landlocked states’ rights to access the oceans through negotiation or binding arbitration.

Chapter 5 demonstrates that states have accepted obligations of mandatory cooperation with respect to a variety of other transboundary harms, including piracy, terrorism, and at least some cyberattacks.

Chapter 13 concludes by recapping the book’s key themes, considering potential obstacles to mandatory cooperation, and identifying other matters of international concern, such as pandemics, that are good candidates for mandatory cooperation under the equitable conception of sovereign equality.

Chapter 10 examines whether states bear duties of international cooperation with respect to forced migration, including the mass displacement caused by Myanmar’s campaign of ethnic cleansing against its Rohingya Muslim minority. It makes the case that the international community has accepted the protection of forced migrants as a common concern of humanity under the community’s joint stewardship.

Chapter 1 draws on the history of Russia’s military interventions in Ukraine to distinguish two conceptions of sovereign equality under international law. It argues that that international law in the twentieth century embraced a constitutional and equitable conception of sovereign equality, generating state obligations to cooperate with one another to resolve disputes over matters of common concern in accordance with equitable principles.

Chapter 3 shows how the international law of the sea moved away from state unilateralism in favor of the equitable model of sovereignty by requiring states to resolve disputes over international fisheries and maritime boundaries through cooperation in accordance with equitable principles.

Chapter 9 explains how duties of international cooperation apply to the international community’s collective responsibility to safeguard international peace, security, and human rights. With the establishment of the United Nations, the Grotian paradigm of states deciding when to use force for themselves shifted to a collective stewardship model whereby states must cooperate with one another to avoid armed conflict, punish atrocity crimes, and combat global poverty, including through collective consultation, negotiation, and peaceful dispute resolution.

Chapter 2 explains how international law governing rivers has evolved to establish a requirement that upstream and downstream sovereigns must consult and negotiate in good faith to determine mutually satisfactory solutions for the shared use of rivers.

Chapter 7 examines climate change as a transnational and existential threat to humanity generally, and to certain smaller and vulnerable states most dramatically. Since it poses an existential threat to low-lying coastal states and raises the frequency and intensity of extreme weather events, Chapter 7 makes the case that climate change should be understood to trigger duties of international cooperation.