Economic damage:
The damage that feral pigs cause is considerable. They eat crops, trample pasture and cause serious soil disturbance when grubbing for plant roots.
The economic effects of feral pig activity in Victoria are currently slight - this is not to say that the present situation will remain indefinitely.
Feral pigs multiply quickly and, unless control measures are implemented as soon as the presence of pigs is detected on a property, populations can rapidly get out of hand. Landowners that allow feral pigs to build up in numbers can face serious problems.
Crop losses are caused when pigs rest or shelter in crops; when they feed on crops near harvest time; and when pigs root up large tracts of ground - often new crops - in a search of roots and young shoots.
Stock losses and a reduction in carrying capacity result from pigs grazing; destroying pasture; or killing large numbers of lambs during the breeding season. Also pigs may foul water supplies by wallowing, making them unpalatable for domestic stock.
There is also the problem of reduced fertility rates among ewes that have been in flocks attacked by pigs at lambing time. Further research is necessary to clarify the extent of this problem.
Environmental damage:
The exact effect of feral pig activities in this area is uncertain. Pigs occupying forests and marshes can damage waterholes. This may have a significant effect on ground-nesting birds because of destruction of nesting sites and habitat.
There is also a possibility that pigs may at times feed on wildfowl and eggs. In the high plains of Kosciusko National Park, pigs are known to feed extensively on tuberous plants, which may threaten individual species or plant communities.
The result of any such alteration in the make-up of an area’s dominant floral species could have adverse effects on those native animals or insects dependent on that environment.
In addition, the general result of extensive disturbances by feral pigs is an invasion of weeds and introduced plants that can alter the ecology of an area completely.
Conclusions:
Feral pigs are one of the most serious vertebrate pest in Australia today. The extent of damage in Victoria is slight. Nonetheless, on individual properties, they can cause serious losses to crops, vines and lambing flocks.
Their potential as reservoirs of exotic diseases is of greatest concern. For the landholder, the control of feral pigs can sometimes appear to be, like the control of rabbits, a difficult and costly exercise that may as well be put off for as long as possible.
It should be remembered that in terms of reduced crop losses, less soil erosion and potentially increased lambing percentages, the expenditure of time and resources is always worthwhile.
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