Regional patterns of continuing decline of the eastern quoll†

Abstract

Like many other Australian mammals, eastern quolls (Dasyurus viverrinus) were widespread in the south-east of mainland Australia but went extinct there during the 20th century. The species remained abundant in Tasmania until it rapidly declined from 2001 to 2003, coinciding with a period of unsuitable weather. We provide an updated analysis of eastern quoll population trends in Tasmania using a time series of annual spotlight counts (1985–2019) collected across most of the species’ range. Eastern quolls were widespread and abundant in Tasmania until the early 2000s. In addition to the previously documented severe decline in the early 2000s in the east and northeast, we present new evidence of an earlier decline in the north (mid-1990s) and a more recent decline in the south (~2009). Declines have continued unabated during the last decade, resulting in a ~67% decline since the late 1990s in the area with high quoll abundance. Although the major decline in the early 2000s coincided with unfavourable weather, the continuing and more recent declines suggest other undetermined causes are also involved. We can no longer assume the presence of eastern quolls in Tasmania ensures the species’ long-term survival, highlighting the urgent need to conserve the remaining populations in Tasmania.