The annual harvest ofTiti, Pujfinus griseus, on islands adjacent to Rakiura (Stewart Island) by Rakiura Maori is one of the last large-scale customary uses of native wildlife in New Zealand. This study investigates whether Rakiura Maori harvesting practices constitute common property resource management and how these practices relate to the sustainability ofTiti harvests. Semi-directive interviews were conducted with 20 experienced Titi harvesters and elders to record their matauranga Maori (Traditional Ecological Knowledge) and tikanga (lore) that govern this harvest. Access to the resource is shared and controlled by birthright. Informal and formal sanctions enforce the rules that promote sustainable use by protecting island habitat and adult birds, and minimising disturbance. These rules and other aspects of Titi harvesting practice conform to common property resource management theory. While adhering to the main resource rules, localised fl exibility in management provides harvesters with the ability to adapt to changing environmental and social circumstances. Adaptive co management ofTiri harvesting has included turning lore into law to reinforce social institutions, integration of science and matauranga for sustainability assessments, and application of new ecosystem management tools. Environmentali ty is promoted by local self-government of Rakiura Maori Titi harvesting practice and island ecosystem management.