Thermal images of common wombats (<i>Vombatus ursinus</i>) taken with a Testo (875-2i) high resolution thermal imaging camera with a 2x telephoto lens.

<p>Shows a healthy wombat (top) and a wombat exhibiting signs of sarcoptic mange (bottom), a disease caused by the S<i>arcoptes scabiei</i> mite. Note the differences in the thermal profile between the two images.</p

A map of the study site chosen to investigate common wombats (<i>Vombatus ursinus</i>) infected with sarcoptic mange.

<p>Narawntapu National Park is shaded in grey [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0149749#pone.0149749.ref042" target="_blank">42</a>]. Reprinted from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0149749#pone.0149749.ref042" target="_blank">42</a>] under a CC BY license, with permission from the Tasmanian Parks and Wildlife Service, original copyright 2010.</p

The burrow emergence time of 20 common wombats (<i>Vombatus ursinus</i>) recorded from March-August 2014 at Narawntapu National Park Tasmania.

<p>Emergence time is not altered by sarcoptic mange (<i>Sarcoptes scabiei</i>), but is strongly correlated with daily maximum temperature. Confidence intervals around regression lines were omitted for clarity of image.</p

<i>Sarcoptes scabiei</i>: The Mange Mite with Mighty Effects on the Common Wombat (<i>Vombatus ursinus</i>)

<div><p>Parasitism has both direct and indirect effects on hosts. Indirect effects (such as behavioural changes) may be common, although are often poorly described. This study examined sarcoptic mange (caused by the mite <i>Sarcoptes scabiei</i>) in the common wombat (<i>Vombatus ursinus</i>), a species that shows severe symptoms of infection and often causes mortality. Wombats showed alterations to above ground behaviours associated with mange. Infected wombats were shown to be active outside of the burrow for longer than healthy individuals. Additionally, they spent more time scratching and drinking, and less time walking as a proportion of time spent above ground when compared with healthy individuals. They did not spend a higher proportion of time feeding, but did have a slower feeding rate and were in poorer body condition. Thermal images showed that wombats with mange lost considerably more heat to the environment due to a diminished insulation layer. Infection status did not have an effect on burrow emergence time, although this was strongly dependent on maximum daily temperature. This study, through the most detailed behavioural observations of wombats to date, contributes to a broader understanding of how mange affects wombat health and abundance, and also to our understanding of the evolution of host responses to this parasite. Despite being globally dispersed and impacting over 100 species with diverse intrinsic host traits, the effects of mange on hosts are relatively poorly understood, and it is possible that similar effects of this disease are conserved in other host species. The indirect effects that we observed may extend to other pathogen types.</p></div

The significant indirect effects of sarcoptic mange on the behaviour of common wombats (<i>Vombatus ursinus</i>).

<p>Wombats infected by mange exhibit changes to time allocations to above ground behaviours: (a) they spend a higher percentage of time drinking water, (b) a lower percentage of time walking, (c) have a slower feeding rate and (d) higher percentage of 30 second time intervals scratching.</p

Elevational shifts upwards of bird distributions.

<p>One of the mechanisms proposed to compensate increments of parasite prevalence at 0, 1, 2 and 4°C increase in temperature. Filled bars represent the predicted distribution of birds with increments of temperature. At 0°C all bars are filled representing the actual distribution of birds along the elevation gradient, with prevalence variation from 64% in the lowlands to 16% at the highest elevations. For each 1°C increase in temperature, bird distributions need to ascend 200 m in elevation in order to avoid an increase in parasite prevalence. Open bars indicate that birds at that site shifted upwards to the next elevation site to avoid an increase in parasite prevalence, leaving that site unoccupied. Failure to make such a distribution shift would potentially result in higher mortality or reduced reproduction because of elevated blood parasite loads. The shifts in parasite loads are likely to be very large. At an altitude of 1200 m, for example, a 4°C temperature rise is predicted to increase parasite prevalence from 16% to 50%. At this higher temperature, only birds that currently live at 400 m or below will be able to offset increases in parasite prevalence by shifting their distributions upwards; for birds currently living above 400 m, some increase in parasite prevalence are unavoidable.</p

Variation of temperature and rainfall at the AWT.

<p>A) Predicted variation of Mean annual temperature as a function of elevation. Temperature decreased at an approximately rate of 1°C per 200 m altitude and there was approximately 1°C difference between the two localities sampled at the same elevation and B) Monthly variation of rainfall at the two localities within the region indicated that the dry season began on May and was extended and acute through November or December when the rainy season began. The highest values of rainfall were between February and May. Localities: South Johnston (SJ) and Carbine Range (CR).</p

Parasite prevalence across host families.

<p>Parasite prevalence of well represented families (1–6; >15 individuals) and other families (7; <15 individuals). Percentage of total number of birds infected and number of birds infected by each parasite genus (%) (<i>Hae: Haemoproteus, Pla: Plasmodium</i>, Unknown: either <i>Haemoproteus</i> and/or <i>Plasmodium</i>, <i>Leu: Leucocytozoon</i> and <i>Try: Trypanosoma</i>).</p

Localities of sampling in the AWT.

<p>The elevation, Mean Annual Temperature (MAT) and Number of sample birds for each locality are indicated.</p

Extrapolations of parasite prevalence with increments of temperature.

<p>Parasite prevalence along the elevational gradient with increments of 0°C (•), 1°C (○), 2°C (▴) and 4°C (Δ), using the equation of the linear regression between overall parasite prevalence and mean annual temperature (temperature –140.62/0.1047 =  parasite prevalence). Extrapolations indicated that there will be an increase of about 10% in the prevalence of parasites for each 1°C of increment in temperature.</p