A population of the Northern Long-nosed Potoroo Potorous tridactylus tridactylus in Tyagarah Nature Reserve on the far north coast of New South Wales was first recorded in 1985. In 1992, a cage-trapping study captured 15 individuals in the central section of the reserve and the population was estimated at 80–90 individuals at that time. A subsequent cage-trapping study in 2004 captured four individuals in the southern section of the reserve, but further cage- and camera-trapping surveys in 2009 and 2012 failed to detect any individuals. Additional camera-trapping surveys between 2012 and 2015 and more intensive surveys between 2015 and 2016 also failed to detect any individuals. The lack of detections from targeted surveys over seven years between 2009 and 2016 suggests that the Tyagarah population of the subspecies has been lost. Reasons for this loss are unclear but may be due to a combination of factors including isolation of the reserve by urban development and highway upgrades, a lack of fire for 40 years, competition for food with the local population of the Australian Brush-turkey Alectura lathami, prolonged drought and possibly, predation by the Red Fox Vulpes vulpes and non-target effects of predator control programs.