Despite proliferation of law and policy directed at halting global biodiversity decline, it is a common concern that decline continues. Using a case study of six New Zealand birds, this article demonstrates reasons for the reduced effect of the law in the context of three international agreements: the Convention on Wetlands of International Importance; the Convention on Biological Diversity; and the Convention on Migratory Species of Wild Animals. The article concludes that the agreements are deficient in terms of obligation and consistency, and that these deficiencies are compounded by insufficient implementation and siloed approaches at the national level. Success is also compromised by the ways in which the law privileges resource use to the detriment of species due to insufficient environment standards, sectoral defences, and widespread externalities. Ironically for birds, mobility which in evolutionary terms has been a survival strategy, may become a liability in the Anthropocene.