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Problems caused by kangaroos and wallabies | FF0019 |
Ian Temby, Flora and Fauna Branch
September, 2003 |  |
Problem
Kangaroos can cause damage to fences, compete with domestic livestock for grazing and water, and graze and trample crops. Some individual kangaroos harass or physically threaten humans at picnic areas where they have become accustomed to being fed by members of the public. Black Wallaby browsing can cause damage to young trees in plantations.
Background
Five species of large marsupials, the Red Kangaroo, the Western Grey Kangaroo, the Eastern Grey Kangaroo, the Red-necked Wallaby and the Black Wallaby, (hereafter referred to generally as kangaroos), may have benefited from the improvement of pastures and the provision of year-round, reliable water supplies, but their distribution is now becoming fragmented as remnant bush areas, used as shelter by kangaroos, are cleared. The range of the Red-necked Wallaby, in particular, has contracted significantly during this century.
The intrusion into agricultural land of kangaroos from Crown land varies in intensity and duration with seasonal conditions and the availability of food on farms. Total damage caused by kangaroos throughout the State may not be great but it can be highly localised and very significant to individual primary producers. Kangaroos generally push through fences, rather than jumping over them. This stretches the wires, making it easier for livestock to get out.
Most rural properties in Victoria are small, by Australian standards. They are mainly cleared of trees and undergrowth and provide little shelter for species of kangaroos naturally associated with forests and woodlands. Further clearing and closer settlement follow the development of hobby farms in some areas. Where this is occurring, kangaroos may congregate on larger neighbouring landholdings where there may be less disturbance and more shelter. However, such an increase in kangaroo density on some properties may lead to increased demand for kangaroo control, putting further pressure on remnant populations in largely cleared areas and increasing the impact of kangaroos on remnant habitat areas. Kangaroos remain common in most parts of the State where cleared land adjoins extensive areas of forested land. The Atlas of Victorian Wildlife can provide details of the current distributions of these five kangaroo species.
It seems likely that access to improved pastures enables the establishment of greater population densities of all five species of kangaroos in the vicinity of such pastures than their adjacent natural habitats alone could support. The advent of effective, kangaroo-proof electric fences, and co-operative fencing schemes, where a number of adjoining landholders co-operate to build a continuous electric fence along their common boundary with forested public land, is likely to lead to significant declines in, or the elimination of, some kangaroo populations, particularly where the remnant habitat areas are relatively small. These fences also serve as a barrier to the movement of kangaroos (and, potentially, other wildlife species) between sub-populations, with possible long-term adverse effects on the genetic diversity of remaining populations. Such fencing could lead to severe damage on areas of remnant vegetation to which kangaroos are restricted.
The future of isolated kangaroo populations that use relatively small areas of remaining native vegetation for diurnal refuge, is more likely to be assured under a regime of controlled shooting, to keep numbers at acceptable levels, than in the event of an increase in the use of electric fencing, as outlined above.
Some people believe that kangaroos transmit internal parasites to domestic livestock. This belief is groundless since most internal parasites of kangaroos are specific to marsupials. Two exceptions are the liver fluke and the hydatid tapeworm, that have been recorded from the Black Wallaby. It is thought that the liver fluke was introduced to Australia with domestic livestock and has been transmitted to native herbivores. Neither of these parasites can be transmitted from marsupials directly to livestock. The belief that footrot can be carried by kangaroos and transmitted to livestock is also false. Hydatids could be transmitted to farm dogs fed with uncooked offal from Black Wallabies. Any offal fed to dogs from this species should be cooked first.
Kangaroos only compete with livestock for pasture when total grazing pressure exceeds dry matter production. To estimate the contribution of kangaroos to total grazing pressure, research has shown that one dry sheep equivalent (DSE) equals 1.6 kangaroos or one kangaroo equals 0.625 DSE. In addition, the contribution of rabbits to the total grazing pressure may be considerable. It is estimated that eight to ten rabbits equal one DSE. Often, alleged kangaroo damage to pastures or crops is due, at least in part, to rabbits. Grazing by kangaroos (and rabbits) does, however, reduce potential yields of hay.
Kangaroos are selective feeders. Studies in rangelands in western NSW have shown that there is very little overlap in diets between kangaroos and domestic stock. During droughts this overlap is further reduced in such areas. The situation in northwest Victorian rangelands, where there is considerable diversity in available plant species, may be similar. There is likely to be greater dietary overlap, however, on improved pastures in southern Victoria, where the available forage comprises relatively few species, most of which are grasses.
In an effort to develop efficient controls of damage caused by Black Wallaby browsing in plantations, the efficacy of shooting, tree guards, repellent treatment of trees, electric fencing and commercial deer fencing have been evaluated. In the past, the poison 1080 was used for wallaby and rabbit browsing damage control in plantations. This poison is no longer used for routine control of browsing damage by Black Wallabies, although it may still be used for rabbit control.
Under some circumstances, kangaroos which lose their fear of humans, either through being fed at picnic grounds or through having been hand-raised, may attack and injure people, mainly by kicking with the hind feet. Large, male kangaroos are particularly dangerous in this situation.
Solution
Electric fence configurations are now available which will keep most kangaroos out most of the time. An electric fence design gaining increasing acceptance is a 45 degree,
12-wire sloping electric fence which leans into the paddock (Figure 1). The second, fourth, sixth and eighth wires are live, with the next three carrying an induced current. This design is capable of excluding kangaroos as well as foxes and other species.
Figure 1. Wire spacing for sloping electric fence (Wire spacing in mm, Post length 2.13 m).
A gate that allows kangaroos through fences without loosening fencing wire has been developed in Western Australia (Figure 2).
Figure 2. Swing gate design.
Sheep and cattle will generally not use these gates. Install swing gates at well-used access points in fences, to reduce further fence damage and enable the fence to be kept tightly strained.
Harass kangaroos frequently, using vehicles, loud noises (e.g. Bird Frite cartridges) and lights. This may help to minimise the time these animals spend on a particular property. Note that vehicles may not be used to chase kangaroos. Similarly, dogs shall not be used to kill, injure or pursue wildlife.
It may sometimes be possible to lessen or avoid a damage problem by, for example, undertaking cropping in an area further away from kangaroo harbour, where harassment is likely to have a longer residual effect. Where kangaroos are entering a property primarily to get water, the provision of small dams in adjoining bush areas may help to resolve this problem. Any decision to undertake this action would have to follow consultation with the managing authority of that land. Such dams could also function as an emergency water source in the event of fire.
Do not feed free-ranging kangaroos, or encourage close contact with kangaroos, as they can be dangerous. If you are attacked by a kangaroo, and you cannot get away, you should lie on your stomach and cover your head with your arms. A kangaroo cannot kick you if you are lying down, and is likely to lose interest in you.
An Authority to Control Wildlife may be issued by DSE to enable a reduction in the size of a local kangaroo population to reduce damage. Contact the DSE Customer Service Centre on 136 186 for an application.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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