Incidence of sarcoptic mange in bare-nosed wombats (Vombatus ursinus)

Abstract

Sarcoptic mange is a threat to bare-nosed wombats (Vombatus ursinus) in Australia and a major factor contributing to the decline in populations of this species. It is caused by a mite, Sarcoptes scabiei, and if untreated can lead to severe irritation, blindness, starvation and eventual death. Modes of transmission likely occur through direct contact between wombats and indirectly from wombat burrows. Our study aimed to estimate and compare the numbers of bare-nosed wombats at three study sites, and to determine how rainfall, temperature and humidity influenced the incidence of sarcoptic mange in the populations. The abundances of macropods and rabbits were also compared with wombat abundance and sarcoptic mange prevalence at the three study sites. Across the study sites, 1655 bare-nosed wombats were observed. Sarcoptic mange prevalence was between 7.0% and 40.7%, depending on site, season and year. Sarcoptic mange prevalence correlated with yearly rainfall, with a higher incidence of sarcoptic mange occurring in higher-rainfall years. Higher numbers of macropods in the study areas also correlated with higher incidences of sarcoptic mange in the wombat populations.

Long‐Term Spatiotemporal Dynamics and Factors Associated with Trends in Bare‐Nosed Wombats

“…These results show that over the last 3 decades, the overall population of wombats both on mainland Tasmania and more recently on Flinders Island have increased. These results also identify areas that could be prioritized for management interventions that may mitigate known threats (e.g., roadkill mitigation; Hobday and Minstrell 2008, Fox et al 2019), and the potential value of spotlight monitoring for populations on mainland Australia (Stannard et al 2020). This study is applicable to other marsupial and wildlife species observable by spotlight in Australia and beyond.…”

“…Similarly, we included spotlight counts of European rabbits in analysis because they are a potential competitor of wombats (Cooke 1998, Stannard et al 2020). Similar to devils, we detected several positive relationships between rabbit and wombat records.…”

“…Rabbits may only be significant competitors of bare‐nosed wombats where their abundance is high, or where food resources for both species are limiting, such as at the western limit of the bare‐nosed wombat distribution (Cooke 1998). Stannard et al (2020) also investigated relationships between spotlight counts of bare‐nosed wombats and rabbits in New South Wales and did not report any notable association. Wombats may compete with other sympatric herbivores, such as forester kangaroos (called eastern grey kangaroos on the Australian mainland).…”

“…Bare‐nosed wombats are protected within each State they occur, and in Tasmania they, and their burrows, are protected under the Tasmanian Nature Conservation Act 2002. Major threatening processes include habitat destruction and alteration (McIlroy 1995, Buchan and Goldney 1998), other anthropogenic interactions (e.g., landholder conflict, collision with vehicles; Ramp et al 2005, Hobday and Minstrell 2008), predation by feral species (Banks 1999), and disease (Skerratt 2005, Martin et al 2018 b , Stannard et al 2020). In almost all cases, the contribution of natural and anthropogenic factors shaping wombat populations remain unknown.…”

“…Capture‐monitor and capture‐recapture studies are possible but are spatially restricted, labor‐intensive, and inherently short‐term (<0.1–1.5 yr; Brown and Taylor 1984, Skerratt et al 2004, Evans 2008, Matthews et al 2013, Martin et al 2019 c ). Other population studies of wombats have used spotlight and camera techniques (direct observation), abundance of burrows, and distribution of their distinctive cube‐shaped scats (indirect observation; Cooke 1998, Story et al 2014, Martin et al 2019 b , Stannard et al 2020). The longest published population studies of bare‐nosed wombats, based on burrow monitoring, span fewer than 3 years (McIlroy 1973, Triggs 2009, Story et al 2014, Martin et al 2019 b ).…”