Wombat burrows are often spectacular because of the soil that has been excavated but they aren’t usually a cause of soil erosion.
FEATURE Ken Slee
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One of the often-quoted sins of introduced deer is that “they cause soil erosion”. This is ascribed to the fact that they have hard hooves rather than the soft foot pads of native wombats and kangaroos.
I have always wondered about this claim as I have never seen any evidence of it in the bush, although, admittedly, the majority of my experience is with sambar and hog deer in Victoria.
Not satisfied with just dismissing the conservationists’ claims, I decided to search the scientific literature to see if any formal investigations had been made into the issue. After several hours searching on Google Scholar I found only one relevant report and none that compared erosion caused by deer with that due to native wildlife (it is obviously not a high priority subject for research).
That one report by Bennett in the Journal of Zoology, published in 1999 with the title ‘Foot areas, ground reaction forces and pressure beneath the feet of kangaroos, wallabies and rat kangaroos’ includes a statement “The findings support the commonly held belief that introduced grazing animals may cause greater mechanical disruption of the soil surface, leading to increased rates of soil erosion, than Australia’s indigenous grazing fauna.”
Bennett’s use of the word “may” is telling - there are so many factors to take into account in an investigation such as this that absolute conclusions cannot be drawn. However, it does seem that there may be some basis to the suggestion that hooves are more likely to cause erosion than pads.
Whether a relatively small number of deer cause significant erosion among tens of millions of cattle and sheep in Australia is another matter – in theory maybe yes, in reality almost certainly no!
Although my search of the scientific literature did not exonerate the deer, I remain convinced that any impact that they have on soil erosion is insignificant and that cattle and sheep, plus land-clearing, land slips, roading, heavy rainfall and flooding (particularly after wildfire) are much more involved and of infinitely greater concern.
The “soft pad” tracks of a kangaroo compared with the “hard hoof” tracks of a sambar.
The “soft pad” tracks of a kangaroo compared with the “hard hoof” tracks of a sambar.
Soil erosion is not a feature of game trails used by deer, kangaroos and wallabies in forest country.
Sambar wallows, like wombat burrows, move soil but very rarely cause soil erosion.
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